Christopher Hughes lured Martin Kok, 49, to his death before he was shot eight times by a gunman in Laren, the Netherlands, on December 8, 2016.
The 33 year-old was a high ranking member of the feared crime clan which had worldwide connections including with Colombian drug cartels and the Italian mafia.
On the instructions of the mob, Hughes met Kok at an Amsterdam hotel then the Boccaccio sex club and alerted others to where he was.
As the pair later left - and Hughes patted a cat outside - double murderer Kok was gunned down as a "favour" for seemingly crossing Moroccan-based gangsters.
Hughes was quizzed by Dutch police the next day before being allowed to leave. He remained at large as the international probe into the brothel shooting continued.
It was his apparent confession to a fellow gang member turned supergrass which lead to his downfall.
Hughes was caught at a hotel in Turin in Italy in January 2020 and returned to Scotland on a European Arrest Warrant.
He now faces a life sentence after being convicted at the High Court in Glasgow of Kok’s murder and involvement in serious organised crime between July 2013 and January 2020.
The killing - despite happening abroad - was investigated as part of the huge Police Scotland probe Operation Escalade, which has already seen a string of gang members jailed for a total of more than 100 years.
The mob are said to be at the “top of the chain” for drug trafficking in the UK while also having an “unprecedented” arsenal of firearms at their disposal.
The clan forged links with international mobsters and mingled at showbiz parties with famous names, including on a luxury yacht to the Abu Dhabi Grand Prix where rappers 50 Cent and Nicki Minaj were on board.
Hughes, a trusted member, was listed by HMRC as “unemployed” - but £40,000-a-week “wages” earned him a luxury lifestyle in The Algarve.
The supergrass said he was told to set a meeting up in an Amsterdam hotel between Hughes and Kok.
Kok - a convicted murderer - was latterly a crime writer who had set up a website exposing criminals in his homeland.
The informer said he believed the meeting was to discuss advertising for the firm's encrypted phone company MPC - funded with £1m of dirty money - on Kok's new crime TV show.
The killing was originally due to happen outside a hotel but Hughes, originally from Glasgow, later told the informant the gun had "jammed".
The murder happened later that night as Hughes paid for Kok's evening at the sex club and supplied him with cocaine.
The informant said: "He [The boss] had been on about someone waiting for Martin Kok and Christopher Hughes was to hold back.
"Martin left just ahead of Chris and he made a comment about a cat appearing at the club and that he stepped back to pet it."
Asked what the significance of petting the cat was, the witness replied: "Martin was going to his car first so there was no mistake of anyone being caught in the crossfire."
Sentence was deferred.