Ali Harbi Ali, the son of a former media adviser to an ex-Prime Minister of Somalia, has been arrested by British police under anti-terrorism laws following the killing of lawmaker David Amess, a source close to the investigation and British media said.

Amess, 69, from Prime Minister Boris Johnson’s Conservative Party, was knifed repeatedly as he met constituency voters in a church on Friday in Leigh-on-Sea.

Police said they had arrested a 25-year-old British man at the scene on suspicion of murder. They have not named the suspect.

A British source close to the investigation named Ali Harbi Ali, a British citizen, as the detained suspect.

Harbi Ali Kullane, the father of Ali Harbi Ali, told The Sunday Times that his son had been arrested in connection with the murder.

“At this particular moment we are going through (an) unprecedented and horrific situation,” Harbi Ali Kullane, a former adviser to Hassan Ali Khaire, a former Somali Prime Minister, told Reuters in an email.

“Due to the ongoing early investigation I am obliged and commanded not to talk about it,” said Harbi Ali Kullane, who is a former director of the Somali government’s media and communication department.

British police were on Sunday searching an address in north London linked to Ali Harbi Ali.