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This week we take a look at TRADEBOM, the FBI’s investigation into the World Trade Center bombing.   We examine how the case broke after one of the bombers foolishly went back to the rental company to try to get a refund on the van they had blown up.  Then we look at some of the problems the FBI encountered, from extremely dubious eyewitnesses to their own explosives expert giving false testimony.  This led to confrontations in court and a very critical Inspector General’s report.  We round off looking at how the case set legal precedents for the 21st century War on Terror.  I also attempt an impression of Mohammed Salameh.


The FBI’s investigation into the WTC bombing – codenamed TRADEBOM – prosecuted the right people. In the last episode we looked at the Emad Salem distraction and the false conspiracy theory that the FBI were somehow behind the bombing. As with a lot of conspiracy theories this gives the theorists a convenient excuse for not having to look at the three trials resulting from the TRADEBOM investigation – they can simply dismiss these as show trials without reading one word of one page of the transcript. As someone who has read every page of the transcripts of two of these trials, I consider that intellectually lazy, evasive and downright stupid.

That being said, there are some big problems with the TRADEBOM investigation, in particular the forensic science concerning the bomb itself. This led to a few embarrassing moments in court and a Department of Justice Inspector General’s report that slammed the FBI’s supposed bomb expert for repeatedly misleading statements catered to the prosecution’s case. That is what we will focus on today.


The first major break in the investigation came when forensic examiners found remnants of a rented Ryder truck in the rubble of the WTC blast. Only hours after the bombing, investigators found parts of the truck’s gear assembly, which fortunately provided them with a VIN (vehicle identification number). This led them back to the rental agency where Mohammed Salameh had hired the truck, and enabled them to lay a trap. Staff at the agency explained that Salameh had been back to their office since the bombing, claiming that the truck had been stolen and looking for a refund of his money. Salameh only had enough money to buy a child’s airline ticket to Jordan to flee the US authorities, and needed the refund to upgrade the ticket to an adult fare.

The FBI put an undercover agent in the office of the rental agency and waited for Salameh to come back with a police incident number to prove that he had reported the van stolen. When he returned, the manager handed Salameh over to the undercover agent, William Atkinson, who explained that he was with the company’s loss prevention unit. It was a ridiculous exchange.

‘But what we’ve done,’ began Atkinson, ‘We, there’s a lot of stolen cars in New Jersey…’

‘Yes’, interrupted Salameh.

‘…more so than any other state in the union.’

‘Yes. And New Jersey I called,’ replied Salameh. Atkinson persisted.

‘What we’re trying to do, we’re trying to put an end to that, and we’re doing it by help of our customer representative and our customers. Maybe you can help us, if I can just get some information.’

‘I will tell you now what’s happened?’ Salameh asked.

‘All right, let me just run through this, it will take you…’

‘Today’s Thursday,’ began Salameh.


‘Like this day, but in the night, ah, I go again to increase my language.’ Salameh went on to explain that the van had been stolen from the car park at a shopping centre, and that he had only realised it was gone when he came back with his shopping.

‘How many parcels did you have?’ Atkinson asked.

‘In, inside it?’

‘Were you carrying.’

‘Ah, three. Three bags. Three small, small, eh.’

‘Three bags,’ repeated Atkinson.


‘Three bags full, sorta like, ah…’

‘What you…’ interrupted Salameh.

‘Baa baa black sheep, have you any wool…’

‘Yeah,’ replied the confused Salameh. The FBI man’s joke had fallen on deaf ears. Salameh then decided that he wanted to be refunded the money he had spent on filling up the van’s petrol tank.

‘I want justice,’ he insisted. Atkinson offered him $200. ‘Is not justice. This is not justice!’ Salameh responded.

‘Well, but it’s business.’

‘I know business, but eh, eh, I need justice, some justice. I paid $400, he told me I need deposit. No justice! We need justice now.’

‘All right,’ Atkinson negotiated, ‘how about $250? Would that get you out of here, $250? Now we’re taking the burden.’

‘Now listen to me,’ Salameh hit back, ‘Now, I have a good idea. Eh, two days and a half, two days and a half.’

‘Is $200,’ explained Atkinson. ‘Half of four hundred dollars is two hundred dollars.’

‘That’s good.’


‘I see this is justice.’ Salameh had managed to argue the agent out of the extra $50 that he was offering. He asked the undercover man his name.

‘Bill,’ Atkinson replied.

‘Bill, thank you very much,’ said Salameh, and walked out of the office, where he was promptly arrested. The information gleaned from his possessions led the authorities to Salameh’s co-conspirators, and in September 1993 the DA indicted Salameh, Mahmud Abouhalima, Ahmed Ajaj, Nidal Ayyad, Ramzi Yousef and Abdul Yasin. Yousef and Yasin aside, the defendants went on trial in late 1993, and were all found guilty in 1994. Yousef remained at large until 1995, but was eventually convicted of the bombing. Yasin fled to Iraq, where he was arrested and held in prison until at least 2002, when he was interviewed by CBS, though nothing has been heard of him since.

The Forensic Science in TRADEBOM

Following Salameh’s idiotic behaviour at the rental agency TRADEBOM proved a relatively straightforward case for the FBI. They quickly found the flat used to build the bomb, including numerous fingerprints belonging to Salameh and Ramzi Yousef. They also found the storage locker where the pair kept the chemicals they bought to produce the bomb, again full of fingerprints and other evidence pointing to Salameh and Yousef. In truth, aside from Yousef and Yasin, the bombers did very little to escape or cover their tracks.

Nonetheless, there were still some problems for the FBI’s case. The most serious problem emerged in the forensic evidence presented at the trials. David Williams was working in the explosives section of the FBI’s crime laboratory in 1993, and was on the scene at the WTC within hours of the explosion. Though initial reports blamed the blast on an electric generator, Williams was quickly convinced it was a bomb and told James Fox, the chief of the FBI’s New York office and de facto head of the TRADEBOM investigation. Fox wanted to know why he was so sure it was a bomb. ‘I have examined ten thousand bombings,’ replied Williams. ‘That’s good enough for me,’ responded Fox. Perhaps encouraged by this personal vindication, Williams proceeded to determine the composition of the bomb by almost pure intuition, and ended up provoking a major internal investigation at the FBI.

Williams testified at both the 1993-4 trial (US vs Salameh et al) and at the followup trial in 1995 (US vs Rahman et al), in both cases providing evidence that helped convict the defendants. After the first trial another scientist in the FBI lab raised objections to the way the forensic evidence had been examined and interpreted in the TRADEBOM case. His name was Frederic Whitehurst, a forensic chemist at the lab who specialised in explosive residues, and he was a major defence witness in the Rahman trial. Whitehurst testified that the preliminary theory in the investigation was that the main charge of the bomb was urea nitrate. He was then asked if he experienced ‘pressure from within the FBI to reach certain conclusions that supported that theory of the investigation,’ and replied ‘yes, that is correct’. He was asked if he was aware that ‘such a finding would strengthen the prosecution of the defendants who were going on trial in that case’ and responded ‘Absolutely.’

It emerged from his testimony that he had arrived at the WTC the day after the explosion and was tasked with doing chemical analysis of the residues found at the scene. Whitehurst explained that traces of urea and traces of various nitrates can be found almost ubiquitously as they are very common substances. When they found out that a report written by David Williams was concluding that a urea nitrate bomb was used, Whitehurst and his partner objected. They argued that the interpretations of the instrument analysis of chemical residues were ignoring the fact that urea and nitrates are common substances. He also testified that he was concerned that ‘other substances, when tested by that instrument, could give a signal which was the same signal they would give if they were urea nitrate even though they were not urea nitrate.’

When they met with resistance from Williams, the technicians who had done the analysis and various supervisors, Whitehurst and his partner Steve Burmeister prepared two samples for testing. Burmeister bought some fertiliser and prepared a solution containing it. Whitehurst, ‘took a 250 ml beaker to the men’s room and urinated in the beaker.’ He then dried the urine and prepared a solution. They labelled the samples ’40 Pamrapo’and sent them to the technician for analysis. The bomb factory where Salameh and Ramzi Yousef built the bomb was at 40 Pamrapo Avenue.

Whitehurst recalled that, ‘We got the same results from the analyses of those two materials that he got from material he felt was urea nitrate.’ Perhaps unsurprisingly, this news was not received well at the FBI lab, and Whitehurst was accused of having contaminated the urine sample with urea nitrate. He even testified that his reports on analysis of the bomb site were rewritten by Williams, and that he was warned against giving information to the defence lawyers that might weaken the prosecution’s case. In what appears a cynical punishment like that meted out to Nancy Floyd, Whitehurst was moved against his will from explosive residue analysis to paint analysis.

The OIG Report

Though Rahman and the other defendants were convicted, the fallout from Whitehurst’s testimony was considerable. He had made a number of allegations about numerous cases handled by the FBI’s laboratory, which provoked an investigation by the Department of Justice’s Office of the Inspector General. The report vindicated many of Whitehurst’s complaints and criticisms, though others were refuted. Whitehurst is now executive director of the Forensic Justice Project and is widely respected as a whistleblower. I confirmed most of this information with him personally.

Regarding the WTC bombing the report focussed on the testimony of David Williams at the two trials. In the Salameh et al trial Williams testified that in the course of the investigation that he made test samples of urea nitrate and even a 1,200 pound bomb that was detonated at Eglin Air Force base. Williams further claimed that he had used some of the chemicals, and followed formulas written in the ‘blue manuals’, both seized in raids on addresses connected to the suspects. As such, his testimony was almost perfect in its support for the prosecution case.

There was a problem. Almost everything Williams had said was partially or completely untrue. As detailed in the OIG report, ‘Personnel in the FBI Laboratory made several batches of urea nitrate prior to the Salameh trial’, but ‘no one in the FBI used the formulas from the blue manuals to manufacture urea nitrate.’ Williams was involved in the production of a large amount of urea nitrate at the Eglin base, but not in the process of determining the chemical formula. Instead, his role ‘was to provide manual assistance under the direction of Whitehurst and Burmeister’. The Office of the Inspector General concluded that ‘Williams’ testimony concerning the use of the Arabic formulas was seriously flawed.’

Among the ‘numerous errors’ made by Williams in his Salameh trial testimony was his supposedly ‘expert opinion’ of the damage caused at the WTC, and his conclusion that it was attributable to 1200 pounds of urea nitrate. As the report notes, ‘Normally, the way a crime laboratory determines the main charge of an exploded bomb is by finding unconsumed particles or distinctive by-products of the explosive among the residue… One problem for the prosecution in the World Trade Center case was that the chemists did not find any residue identifying the explosive. Thus, the normal way of scientifically determining the main charge was unavailable. Williams’ purported identification of the explosive filled that void.’

So how did Williams make his assessment? He examined the scene himself, and made what he tried to make out was an educated estimate. In reality, it was glorified guesswork and assumption. Williams explained in his testimony that he had been on a ‘two and a half hour walk-through’ of the bomb site and inspected much of the damage. This led him to a conclusion of the power of the explosive used, specifically its velocity of detonation (VOD). He said, ‘By putting all of these things together and looking at the size of the hole I estimated that the velocity of detonation was somewhere between 14,000 and about 15,500 feet per second.’ Unsurprisingly, the OIG report states that, ‘We conclude that Williams’ VOD opinion lacked a sufficient scientific and empirical foundation.’

For one thing, Williams had shown remarkable inconsistency in his estimates of the VOD, citing different figures in his written report, his testimony at the two trials, his interview with the OIG and a letter he wrote to the OIG. The report noted that, ‘Williams has given four estimates of the VOD: approximately 14,000 feet per second (his report), 14,000 to about 15,500 feet per second with a little give on each side of that (Salameh trial), around 14,000 feet per second with a bracket on both sides of a couple thousand feet (Rahman trial, OIG interviews), and between 11,000 and 16,000 feet per second (letter to the OIG).’

The reason for these changes was that people kept pointing out to Williams the problems with his estimates. After testifying at the Salameh trial that the range was 14,000 to 15,500, Williams ‘discovered’ that in the mock-up explosion at Eglin the urea nitrate exploded with a VOD of 12,100 fps. This led to the new estimate at the Rahman trial of 12,000 to 16,000. The OIG found among Williams’ notes for the TRADEBOM investigation copies of pages from explosives encyclopaedias stating that urea nitrate has a VOD range of 11,155 to 15,420 feet per second. When they presented this information to Williams he once again changed his estimate, to between 11,000 and 16,000. The report noted that each change enabled Williams to maintain his desired conclusion that urea nitrate was used, saying, ‘The circumstances of the four estimates imply that Williams changed his VOD opinion for the main charge in order to maintain a match with the VOD of urea nitrate.’

Another problem is that Williams’ method of estimation of the VOD left a lot to be desired. During his inspection of the bomb site he claimed to have identified damage that supported his estimate of 14,000 to 15,500 feet per second. He explained in his Salameh trial testimony that a more powerful explosive such as C4 would cause ‘tearing’ of steel beams, whereas he saw only ‘pushing and heaving’. The OIG noted that, ‘The problem with this testimony is that Williams never explains how the observations compute to 14,000-15,500 feet per second.’ The lack of tearing only ruled out the use of high-grade military explosives, but still left the possibility of explosives anywhere in the range below that, such as TNT or Acetone Peroxide.

When the OIG put this to Williams he elaborated on his explanation for his estimate, saying that he had looked at the bodies of the victims of the explosion, how far they were from the centre of the blast, and damage to various other items. From all this information put together he derived his estimate. He was asked if the literature on explosions supported his statements about damage to bodies and so on and he replied, ‘Yes, it would.’ When asked about whether the literature supported his contention that a qualified expert could make a VOD estimate on the basis of such an examination, Williams replied, ‘I don’t know.’ The OIG report concluded that, ‘We find Williams’ application of his methodology flawed, because it is essentially an unscientific, unverifiable process of intuition… The application of the methodology is one of rough feelings, guesses, and impressions. There was a complete absence of empirical data to support any of the inferences Williams made from the various factors he identified.’

The OIG found that Williams account, from his reports to his trial testimony to his communications with the Inspector General, was scientifically flawed and presumed the guilt of the defendants. In summary they wrote, ‘Williams gave inaccurate and incomplete testimony and testified to invalid opinions that appeared tailored to the most incriminating result.’ They recommended that Williams not just be removed from the explosives unit, but that he be reassigned outside of the FBI’s Crime Laboratory altogether. They also recommended that ‘a qualified examiner review any testimony after it is given to assure that Agent Williams has limited his testimony to reasonably supportable conclusions.’ As Neil Herman, a senior FBI investigator with the JTTF, commented on the WTC prosecution case, ‘The evidence, to be perfectly honest with you, is not overwhelming.’ Despite these problems, every person who went on trial in connection with the bombing was convicted.

Differing accounts of the bomb used at the WTC

Another factor to consider is the wildly differing accounts of what was in the truck bomb used to kill those 6 people and wound around 1000, some of whom were quite horribly injured. According to the prosecution’s case and his own confessions, Ramzi Yousef arrived in New York with Ahmed Ajaj in early September 1992, spent six months acquiring the chemicals and building the bomb, blew up the WTC and left the US for Pakistan that evening. We will get into Ramzi’s complex biography in the next episode, all you need to know for today is that he was captured in Pakistan in February 1995 and extradited to the US. On the plane he made an extended confession to two FBI agents, and later even had proffer sessions with the FBI and Department of Justice.

I gained copies of the FBI 302s detailing these confessions, and during his proffer session where Ramzi considered pleading guilty he provided an extensive description of the bomb:

He described the main charge as urea nitrate, contained in a wooden box of his own construction. The box was largest in its horizontal dimensions; the sides of the box were not as large as its top and bottom dimensions.

The main charge was boosted by three separate boosters, each with its own detonator. He described the boosters as follows:

1) Thirty (30) kilograms (kg) of dynamite, which he manufactured from 70% ammonium nitrate, 29% nitroglycerine, and 1% nitrocelulose.

2) Twenty (20) kg of a mixture of ammonium nitrate, nitromethane, and analine (94% nitromethane and 6% analine mixed, then 1/3 of this mixture added to 2/3 of ammonium nitrate, by volume, not by weight).

3) Fifty (50) kg. of thermite, manufactured by him by mixing ferric trioxide, magnesium powder, aluminium powder and some glycerine.

In between bombing the WTC and getting captured in Pakistan, Yousef spent a lot of time with his old friend Hakim Murad, who was arrested in the Philippines and interrogated by the Philippines National Police. Records of Murad’s interrogation describe a quite different bomb recipe, even though he apparently got this information directly from Yousef. Murad described ‘a small quantity of astrolite bomb; made of Ammonium Nitrate and Hydrazine liquid’ and a ‘small quantity of Lead Azide’ and a ‘large volume of chemical bomb made out of Nitric Acid in a drum’.

These two bomb recipes don’t match up, and if you read books about the bombing they often add in other details like big canisters of gas and even cyanide. So exactly what was used to blow up the WTC is not clear. However, the bomb caused a gigantic crater, smashing through several floors of the underground parking garage beneath the WTC and blasting a 5000 square-foot hole in the floor above the bomb.

Could one urea nitrate bomb do this much damage? Some obvious comparisons are available – the FBI and the US Air Force did multiple test explosions following WTC93 and the Oklahoma City bombing in ‘95. They found that the bombs they built did not do the same degree and type of damage that they apparently did in New York and Oklahoma City. This has led to theories and claims that the yellow rented Ryder truck driven by Tim McVeigh in Oklahoma City was not the primary cause of the deaths and damage there. Though I’ve not seen anyone making this argument, I think there’s a similar case to be made about the WTC.

Before we wrap up today I want to tell you one more part of the story of the TRADEBOM investigation – of gas station attendant Willie Moosh. Most versions of the WTC bombing agree that the bombers drove the truck and their getaway car from Pamrapo Avenue in Jersey City into New York, left the truck bomb at the WTC and then drove away in the car. One of the problems for the prosecution is that no one saw any of the defendants at the WTC, so they needed another witness to connect them to the truck and therefore to the bomb.

They found Willie Hernandez Moosh, an attendant at a petrol station in Jersey City who said he saw the two vehicles and some of the defendants getting petrol at 3 a.m. that morning. He testified at the first WTC bombing trial that he had seen a yellow Ryder van and blue Lincoln Town Car that morning, and he was asked to identify the two men he had seen driving the vehicles. Moosh was expected to point out Mahmud Abouhalima and Mohammed Salameh, but after getting down from the witness stand and looking around the courtroom, he identified two members of the jury.

According to Yousef, this is because they were never at the petrol station in Jersey City at 3 a.m.. In his proffer session he explained that Salameh had forgotten to wake him up early that morning, so they got started late. Yousef also said that they stayed in a hotel in Brooklyn the night before the bombing, not in the apartment in Jersey City. So it seems everything Moosh said was untrue, and despite being the only government witness to identify any of the suspects on the day of the bombing, the jury convicted.


Amidst all the conflicting evidence, speculation, secrets, and conspiracy theories, historians will find it difficult to determine exactly what happened on and around the 26th February 1993. Exactly where and why the plot originated, who was responsible and how they did it are not particularly easy questions to answer. I am pretty sure that Yousef did build the bomb and that most if not all of the people who were convicted and imprisoned are guilty.

However, we should also be looking inward, at the connections between the conspirators and our own intelligence services, and those of our allies. As we will explore next time there is strong evidence implicating the ISI in helping Yousef, whether or not they knew what he was doing. Similar evidence shows support from the CIA to the Blind Sheikh, and that they knew who and what they were getting involved with at an early stage in proceedings. The Boston Herald reported in 1994 on a CIA Inspector General’s report that concluded that the Agency were ‘partly culpable’ for the bombing. The story reported on a source familiar with the report saying, ‘By giving these people the funding that we did, a situation was created in which it could be safely argued that we bombed the World Trade Center.’ The article went on to say that the report detailed that, ‘a significant amount of blowback appeared to have occurred.’

What was a clear intelligence failure for the FBI was perhaps an intelligence success for the CIA and ISI. Having helped to create a monster in Afghanistan in the 1980s, the murders of Kahane and Shalabi and the WTC bombing were the first signs of that monster stretching its legs. The two murders were barely investigated, but the bombing resulted in a large number of successful prosecutions. Though the Blind Sheikh was courted due to the fears over the rising popular Islamic resistance in Egypt, he was ultimately convicted of a wide-ranging conspiracy. However, the Al-Kifah center in Brooklyn quietly closed down and the organisation reformed in Boston, using the same website and publishing the same newsletter. What this indicates is that after the bombing the Blind Sheikh was considered to be untrustworthy, but the network in which he played a significant role was still seen as useful. There is little, if any, evidence showing that the CIA intended for the bombing to happen, but there is also no evidence of any CIA official being reprimanded as a result of it.

The legacy of WTC93 is largely as a precursor to the contemporary War on Terror. American blood spilt by Muslim terrorists, and at the WTC in New York, was a powerful meme, and helped feed into the new post-Cold War paranoia about Islamic militancy. Six deaths hardly qualifies as a major threat to national security, however horrifying it was for the loved ones of those victims. Nonetheless, the bombing set several precedents, psychological, political and legal, that have become much more commonplace in the over twenty years since then.

Perhaps the best example of this is the treatment of Mahmud Abouhalima. Following the bombing he fled the US and returned to Egypt, his homeland. There, he was detained by the Egyptian authorities, who hung him upside down, burnt his genitals, and threatened to rape members of his family until he confessed to the WTC bombing. They then sent him back to the US wrapped up in duct tape, like a mummy, where he was interrogated by the FBI. He asked one of the US agents if they knew of a man called ‘Rashid’, which was the main pseudonym used by Ramzi Yousef while he was in New York. Abouhalima also corrected one of the agent’s pronunciation of ‘Pamrapo’. The prosecutors later used this as evidence of Abouhalima’s knowledge of and involvement in the bombing plot.

After his conviction in 1994, Abouhalima appealed in part on the grounds that these comments had been made after ten days of imprisonment and torture, and the use of them to help convict him was unfair. The Second Circuit court decided that because the torture had been carried out by agents of a foreign government, and that there was no allegation of coercion by US agents, that this aspect of the appeal was refused. In effect, the court said that a suspect who was tortured in a foreign country and subsequently interrogated by US officials was fair game. This has now evolved into a practice known by the Orwellian euphemism ‘extraordinary rendition’, whereby ‘terror suspects’ are kidnapped and tortured. In those cases where the suspect is lucky enough to actually get to a trial the confessions they made while, or shortly after being tortured are often used against them.