Two men have been questioned by detectives investigating the murder of Pc Keith Blakelock during the 1985 Broadwater Farm riots in north London.
The suspects, aged 52 and 46, were arrested at separate north London addresses on suspicion of murder last Friday.
A Metropolitan Police spokesman said the two men were interviewed and have been released on bail until September.
Mr Blakelock, a father of three, was murdered by a machete-wielding gang 25 years ago during riots in Tottenham.
The police spokesman said the two men, who would have been around 27 and 21 years old in 1985, are both originally from Tottenham.
A third suspect, aged 40, who was arrested in Suffolk in February, also remains on police bail.
The spokesman said: "Police would like to reassure anyone who has information regarding those involved in the murder of Pc Keith Blakelock, or the attempted murder of Pc Richard Coombes who was also attacked and injured during the riots, that they can contact the incident room in confidence on 020 8733 4613."
This year marks the 25th anniversary of Pc Blakelock's murder at the hands of an armed mob.
Pc Blakelock and his colleague Pc Richard Coombes were attacked as they tried to protect firefighters as violence spiralled on the estate.
The unrest was sparked by the death of Cynthia Jarrett, 49, who collapsed during a police raid on her home.
