Role in the Bomb Plot
Ramzi Diab, as he’s known and called herein, is actually an alias for Salah Kwikas , born 24 Sept. 1959, Nazareth , and in 1988 a terrorist connected to the Popular Front for the Liberation of Palestine, General Command (PFLP-GC). Diab was one of over 1,000 Palestinian prisoners released in exchange for three Israelis in 1985 - an agreement negotiated by PFLP-GC veteran Hafez Dalkamouni.  In the fall of 1988, he converged with other GC players, under Dalkamouni’s leadership, in Neuss and Frankfurt West Germany for the plot to destroy American airliners with altimeter bombs.
David Leppard writes how cell ringleader Dalkamouni, after his arrest, told BKA police “he was given the second Toshiba on about 18 October by a man called Ramzi Diab in Frankfurt. It also contained two pressure boxes, two clocks and two platinum plates. Diab, Dalkamouni said, was a member of the military section of the PFLP-GC.”  Ludwig DeBraeckeleer writes that on October 22, the day Khreesat started his bomb-making work with that radio and four other units, “Dalkamoni and Khreesat travel to Frankfurt […] At 2pm, they meet Ramzi Diab,” for uncertain reasons.  The same author notes the earlier meeting, October 18 at 5:10 PM.
In his early thirties, Diab is a member of Jibril PFLP-GC. After their meeting, Diab left in a car that belongs to Bassam Radi, a member of Adnan Younis terrorist cell. Younis, aka Abu Tarek, is also a member of the PFLP-GC. Dalkamouni later identified Diab as “a key player in the Lockerbie operation,” wrote Emerson and Duffy. “a courier of some of the bomb-making materials.”  Two witnesses, Diab’s flatmate Angelika Berner and his “German instructor, a kindly man named German Hoch” recalled a trip to Vienna Austria that Diab said he took in about mid-October. Both later told Emerson and Duffy that the BKA left them with a feeling Diab was thought to have “transported … the materials … to make the bombs,” or “transported the explosive material … of the type that exploded at Lockerbie.” 
Arrest, Release, Flight
When the mass arrests happened on October 26, Ramzi Diab was found at his house on Querstrasse 4, Frankfort-Main.  His documents were deemed fake, and there was no information on his arrest report other than birthdate.  “Under questioning by the BKA, Diab adamantly denied knowing Dalkamouni or being a member of the PFLP-GC,” wrote Emerson and Duffy in 1990. He then recalled meeting the boss, in passing, when presented with photos of him with Dalkamouni. 
He was released the very next day, along with most of those hauled in, for “lack of evidence.” The guns and bombs and any plots were all decided to be on Dalkamouni, Khreesat, and Ghadanfar alone. Like so many others, he fled upon release; Leppard cited a later BKA report that Diab “left the Federal Republic of Germany a few days after being released, present whereabouts unknown, possibly Austria.” 
This flight was probably guessed from the stories of Diab’s acquaintances Berner and Hoch, testifying to an earlier trip thataway. “One witness, a student called German Hock,” Leppard fumbled, “said he had seen Diab leaving Frankfurt on a train to Vienna. Under his arm was a Toshiba radio.”  That’s rather a twist, and unclear if this was the pre-arrest trip or his flight after. At trial, BKA officer Anton Van Treek was asked “when [Diab] was released, was he in possession of a radio/cassette recorder?” and responded simply “I am unable to say anything on that.”  The transcripts also offer a full list of October 26 arrestees, including Diab, released the following day, and, interestingly, his teacher friend German Hoch was among those hauled in, also released on the 27th. 
Diab is sometimes cited as the man who brought in one radio for modification and slipped away with one armed – both tasks also attributed to “Abu Elias.” An anonymous online comment says “one of Khreesat's bombs however, had been smuggled out of the West German apartment by the PFLP-GC terrorist Ramzi Diab.”  In his 1989 series of articles in the Sunday Times, David Leppard explained that the missing fifth bomb made by Khreesat “was smuggled to Malta by a known PFLP-GC terrorist called Ramzi Diab, and handed over to a Palestinian cell there.”  This whole theory died in its infancy, but not before spawning a TV movie.
Wherever he got away to and whatever with, as Emerson and Duffy wrote in early 1990 “Lockerbie investigators would like to find Diab, but they have been unable to do so.” But he wasn’t universally considered a villain; “some senior officials” had suspected that Diab called in the BKA raid, and “the Germans were told by Diab’s handlers that everything was under control” with the one bomb seized. “If Ramzi Diab was the second informant, as some investigators believe, he may not have known about Khreesat’s other four bombs, and if that is so, German authorities would would have been using Diab’s partial truth to confirm Khreesat’s wholesale lie.”  Further, the writers mused:
“For whom was Diab really working? Again, as with Marwan Khreesat, American investigators are not sure. Some believe that he had convinced the Germans that he was genuinely working for them. Others believe he may have been an informant for Israel. Some intelligence officials believe that, in an even stranger twist, there were Syrian informants in or connected to Dalkamouni’s network … just in case [Jibril] was not as forthcoming as he had promised.”David Leppard’s slightly later work On the Trail of Terror stated “the CIA had discovered that the other ‘mole’ inside Dalkamouni’s cell was Ramzi Diab.” The Agency, via lead investigator Vincent Cannistraro, believed Diab may have secured Khreesat’s fifth bomb and “may have taken it back to Syria.” It didn’t go well if so - on his return, Leppard writes, “Jibril is understood to have held a tribunal: he wanted to know how the BKA had managed so comprehensively to wind up his European network” Though Dalkamouni blamed Khreesat, “Jibril drew his own conclusions. Ramzi Diab was executed shortly afterwards.”  DeBraeckeleer says “the tribunal established that Diab was a mole for the MOSSAD.”  It was after this execution, Cannistraro told Leppard, that Jibril contracted with the Libyans to finish the job. 
[1, 3, 10, 11] Emerson and Duffy. pp 134-135
[2, 4, 9] Leppard, David. pp 10-11
 De Breackeleer, Ludwig. “Abu Elias Arrives in Germany: Diary of a Vengeance Foretold, part 112.” Canada Free Press. October 22 2008. http://www.canadafreepress.com/index.php/article/6194
 De Breackeleer, Ludwig. “What a Tragedy, What A Mess… Diary of a Vengeance Foretold, part 108.” Canada Free Press. October 18 2008.
 Emerson and Duffy p 262
 E+D pp 209-211
[12, 13] Leppard 13
 Day 76, p 8718
 p 9358
 Foot, p 6
[18, 19] Emerson and Duffy p 262
[20, 22] Leppard pp 211-212
 PFLP-GC Tribunal Sentences Ramzi Diab to death. Part 124 – NOVEMBER 3 1988