THE alleged ringleader of the terror attacks in Spain had links to one of the 2004 Madrid train bombers and was in Brussels shortly before bombings there last year, according to reports.
Abdelbaki Es Satty is thought to have radicalised the younger members of the cell that attacked Las Ramblas and Cambrils on Thursday.
The suspected mastermind's home has been searched in the wake of the two attacks last week but the 45-year-old is one of three suspects still missing.
When he came out of jail about two years ago, Es Satty became an imam preaching in Ripoll but stopped two months ago, the town's mosque leader said.
He followed the fundamentalist Salafi branch of Islam.
Es Satty's housemate said on Tuesday the imam returned from his home in Morocco where he had dropped his possessions off.
Then he left and a few hours later, there was a massive explosion at a bomb factory.
Police sources have told Spanish media outlet El Pais that he may have been killed in the explosion at one of the terrorists' homes in Alcanar.
The terror cell had 120 gas bottles there that they were planning to use in a major terror plot that went wrong.
At the site of the gas blast, investigators discovered traces of the unstable explosive TATP that was used by IS in attacks in Paris and Brussels.
They believe the group may have planned to combine the TATP with the gas bottles and load them into three rented vans to create a massive explosion.
The Times reports that police are also investigating whether he was involved in the IS assaults on Brussels airport and a Metro station that killed 32 people on March 22, last year.
According to Sky News, Es Satty went to prison five years ago for trafficking hashish from Morocco to Spain, and was locked up alongside Rachid Aglif who had been jailed for his role in the Madrid train bombings that is Spain's worst terror attack with 192 dead and 2000 injured.
Sources in Spain said Es Satty had not been religious before prison and might have fallen under the influence of Aglif and other terrorists behind bars.
Catalan police official Josep Lluis Trapero told reporters the imam was part of the investigation, but said police had no solid evidence that he was responsible for radicalising the young men in the cell.
A woman who had connections to many of the attackers and who had heard Es Satty's sermons said he often preached about jihad and killing infidels.
She said she feared she would be attacked for speaking out and only spoke on condition of anonymity.
She now feels guilty because she "could have done something”.
"Everybody knew it. It was an open secret. But I can't say it because these people are dangerous and they could come after me. I don't trust anybody now,” she told a reporter.
Es Satty's former mosque denounced the deadly attacks even as it denied Es Satty was anything other than "a normal imam”.