British counterterrorism police said today that a terror plot to assassinate Prime Minister Theresa May was tripped up after the would-be jihadist inadvertently contacted an “online role player working with the FBI” last September.

The FBI “in-turn introduced him to online role-players from MI5 and Counter Terrorism Policing,” said British officials.

Naa’imur Zakariyah Rahman, 20, of London was found guilty Wednesday of plotting to set a bomb off at 10 Downing Street and then try to behead May in the ensuing confusion.

Rahman, a Briton of Bangladeshi origin with family in London and Birmingham, was unemployed and living at home with his mom. He reportedly told an intelligence officer posing as an ISIS leader that he was sometimes having trouble sneaking out of the house without arousing his mom’s suspicion.

Dean Haydon, the UK’s senior national coordinator for counterterrorism, in a statement today called Rahman “an extremely dangerous and determined individual.”

“Rahman’s target was the Prime Minister but he had no qualms about killing innocent bystanders in the process of reaching her. In fact, at one point he told a covert counter terrorism officer that even if he could not reach the prime minister, he just wanted to strike fear into people,” Haydon said. “This case demonstrates the strength of the cooperation between the UK’s intelligence agencies and the FBI. As a result, we were able to disrupt Rahman’s plans and ensure that a terrorist attack was prevented.”

In his online chats with undercover officers posing as ISIS, Rahman wrote on Sept. 14, “Can you put me in a sleeper cell ASAP? I want to do a suicide bomb on parliament. I want to attempt to kill Theresa May.”

“My objective is to take out my target,” he said the next day. “Nothing less than the death of the leaders of parliament.”

Rahman reportedly wanted to use extra help to make the explosion as big as possible. “There are lorries here with big gas tankers, if a brother can drive it next to Parliament I will bomb,” he said.

He toyed with potential methods including a drone attack and poison before settling on a bombing and gun or knife.

In November, he carried out reconnaissance on his expected target — he was captured on CCTV during his reconnaissance mission — and gave his backpack and jacket to an undercover officer to be converted into improvised explosive devices.

“Now I’ve seen everything, it feels good,” Rahman lauded the handiwork after an undercover officer gave him dummy devices.

As he left that car meeting, he was arrested. Metropolitan Police released drone footage of the arrest.

Guilty: 20yo Naa’imur Rahman planned a terror attack to kill the Prime Minister. A joint investigation between @terrorismpolice, MI5 and FBI foiled his plot. #ActionCountersTerrorism 📽 Watch: Rahman arrested after covert investigation.

▶ Details: https://t.co/o017LIaIEQ pic.twitter.com/yRCJyBxSGY — Terrorism Police UK (@TerrorismPolice) July 19, 2018

“Every day the counter terrorism network employs a plethora of tactics to investigate terrorism and keep the public safe from terrorists. Covert policing is a crucial tactic and in this case, it enabled us to understand fully what Rahman intended to do and how serious he was about doing it. Covert officers were able to gather the strong evidence for the prosecution, and it follows that the jury have found Rahman guilty,” Haydon said.

“This case is a reminder of the continuing threat from terrorism and the need for us to all be vigilant and report any suspicious behavior,” he added.