POLICE are asking for the public to help them piece together more information about Khalid Masood, the terrorist responsible for the attack in Westminster on Wednesday that left five dead and fifty injured.

Assistant Deputy Commissioner Mark Rowley, of the Metropolitan Police, said they were looking at Masood’s “motivation, preparation and his associates” and were investigating if the killer “acted totally alone inspired by terrorist propaganda, or if others have encouraged, supported or directed him”.

Rowley added: “There might be people out there who did have concerns about Masood but did not feel comfortable for whatever reason in passing those concerns to us.”

Two arrests were made in the West Midlands on Thursday night, bringing the total to 11, though one woman has since been released on bail.

Searches are continuing at five addresses, with 16 property searches having been completed and 2,700 items seized.

It’s a sizeable operation, with police in contact with about 3,500 witnesses, including 1,000 from Westminster Bridge and 2,500 who were on the parliamentary estate during Wednesday’s attack.

“We’re keen to hear from anyone who knew Khalid Masood well,” Rowley said. “Anyone who understands who his associates were, anyone who can provide information about the places he’s recently visited.

More has emerged about the final hours and violent past of the 52 year old father of three. He was was “laughing and joking” in Brighton the night before, according to the manager of the hotel he had stayed in.

“We never thought anything of him. He was just another guest who checked into the hotel,” Sabeur Toumi, of the Preston Park hotel, told Sky News.

Masood discussed his family, saying his father was ill and mentioning his “wonderful children”.

“He was very friendly, laughing and joking,” Toumi said.

Police also said Masood’s fourth victim was Leslie Rhodes, a 75-year-old window cleaner from south London. He died in hospital overnight from his injuries.

The others killed in the attack were PC Keith Palmer, 48, who was fatally stabbed by Masood inside the parliamentary gates; Kurt Cochran, 54, an American tourist, and Aysha Frade, 43, a London teacher.

Rowley said at least 50 people, of 12 nationalities, had been injured, with 31 requiring hospital treatment. “It’s a poignant reminder that the impact of the attack on the capital will reach around the world,” he said.

Prince Charles yesterday visited some of those injured.

Masood has a history of attacking people using a knife. He has a conviction for assault from 2000, when he slashed a man’s face in a pub. At the time he was known as Adrian Elms, and was jailed for two years.

Adrian Baker, who has lived in Northiam for 25 years, said on Friday that Elms was well-known locally.

He said: “I’m gobsmacked. He didn’t appear to be very religious. He would go into the local pubs.

“I do remember a fracas involving a guy called Piers Mott. This was a long time ago. I remember Elms being a bit of a troubled character.”

Scotland Yard also revealed Masood had criminal convictions for grievous bodily harm and other assaults, possession of offensive weapons, and public order offences.

His first conviction was in November 1983 for criminal damage and his last was in 2003, when he was living in Eastbourne, for stabbing a man in the nose.

The attack on Wednesday began at 2.40pm when Masood drove into pedestrians on Westminster Bridge before crashing his 4x4 into the fence outside parliament. He then attacked two police officers, killing PC Palmer, as he tried to enter the building.