LONDON (AP) — Prime Minister Boris Johnson led a somber British Parliament on Monday in honoring the Conservative lawmaker stabbed to death as he met constituents at a church hall, an attack that has raised questions about how the country protects it politicians and grapples with extremism at home.

The tributes from shaken and grieving colleagues came as detectives tried to determine whether David Amess was targeted simply because he was a legislator, or for more individual reasons. A 25-year-old British man with Somali heritage, Ali Harbi Ali, was arrested at the scene and is being held under the Terrorism Act on suspicion of murder. Police say the suspect may have had a “motivation linked to Islamist extremism.”

The prime minister told lawmakers that “this House has lost a steadfast servant.”

“Sir David was taken from us in a contemptible act of violence, striking at the core of what it is to be a Member of this House and violating the sanctity both of the church in which he was killed and the constituency surgery that is so essential to our representative democracy,” he said, referring to the open meetings British lawmakers hold with those they represent.

The death of the popular legislator — who had served in Parliament for almost 40 years and was knighted by Queen Elizabeth II in 2015 — shocked Britain, especially its politicians. It came five years after Labour Party lawmaker Jo Cox was shot and stabbed to death by a far-right extremist. Cox was the first British lawmaker to be killed since a peace accord ended large-scale Northern Ireland violence almost 30 years earlier.

The House of Commons returned Monday from a three-week break for a session that opened with a prayer from the Speaker’s chaplain, Tricia Hillas, and a minute of silence from hundreds of lawmakers in the chamber.

Then lawmakers from all parties stood recall Amess fondly as a hard-working legislator who never sought high office but, as Johnson put it, “simply wanted to serve the people of Essex,” his home county.

Amess, who was 69, was a social conservative who opposed abortion, campaigned for animal rights and strongly supported Britain’s exit from the European Union.

Labour Party leader Keir Starmer, who often differed with Amess politically, said the late lawmaker held his beliefs “passionately but gently,” and his life was a reminder that “civility matters.”