Murder probe detectives will today continue to question a second man about the death of Syrian-born preacher Abdul Hadi Arwani.

Forensic officers were last night scouring the An Noor mosque in Acton, west London, following the arrest of a 61-year-old man on suspicion of conspiracy to commit murder.

Prayer mats were moved outside the front of the building last night as worshippers arriving to pray at the venue were met by uniformed police officers at the entrance, while forensic teams worked inside.

Earlier, 36-year-old Leslie Cooper appeared in court charged with Mr Arwani's murder. He did not enter a plea and was remanded in custody to appear at the Old Bailey later this week.

It came as Mr Arwani's family thanked the community "for the outpouring of support during this extremely difficult time".

In a statement, released through Scotland Yard, Mr Arwani's son Murhaf said: "We are touched to learn how many people my father helped, advised and inspired in his short life."

His father was a critic of the Assad regime in Syria and an imam at the An Noor mosque from 2005 to 2011.

He was found dead in a car with gunshot wounds on April 7 in the Greenhill area of north-west London.

Last night Mr Arwani's son also urged anyone who may be able to help with the investigation to come forward.

He said: "If anyone has any additional information that can help with the investigation, we urge you to please come forward and speak to the Metropolitan Police.

"Your co-operation will help us close this painful page and begin to move on with our lives, in the knowledge that the person who took away our father will be brought to justice and duly punished for this heinous crime."

Mr Arwani was speaking as the second man was arrested in connection with his father's murder.

Counter terrorism officers arrested the 61 year old yesterday afternoon.

As part of the investigation, officers searched addresses in London including areas within the An Noor mosque.

A police spokesman said: "All officers involved in the search of the mosque are sensitive to the impact that their presence will have and are aware that this action may cause concern in the local community.

"We have been in contact with trusted community Muslim advisers this afternoon to reassure them that the action is necessary and that the premises will re-open as quickly as possible."

A spokesman for the mosque said no one was available to comment.