A memorial to a police officer who was shot dead on duty has been damaged by someone who tried to set it on fire.
The stone marks the place in Leeds where unarmed Pc Ian Broadhurst was gunned down on Boxing Day 2003.
West Yorkshire Police said the memorial stone has been "blackened" during an attempt to set it on fire.
A spokesman said some form of accelerant had been poured on to it.
The vandalism was reported to police on Monday by a member of the public and officers believe the damage happened overnight between Sunday evening and Monday morning.
Traffic officer Pc Broadhurst, 34, was shot by former US Marine David Bieber near to the junction of Dib Lane and Grange Park Avenue in the Fearnville area of Leeds.
His colleagues Pc Neil Roper and Pc James Banks were also shot by Bieber.
They incident happened after they saw Bieber's car was displaying false number plates while parked on Dib Lane and they attempted to arrest him.
Bieber, 42, was found guilty of murder and two counts of attempted murder in 2004 and was jailed for life with a recommendation he should never be released.
In 2008 Appeal Court judges said Bieber should serve a minimum of 37 years in prison before being considered for parole.
Chief Superintendent Richard Jackson, the Divisional Commander for North East Leeds, said: "Police officers go to work every day never knowing what could happen and thankfully few never make the ultimate sacrifice made by Ian Broadhurst.
"The memorial is a way for local people, local officers and Ian's friends and family to mark the terrible events of December 26, 2003 and for someone to deliberately vandalise the memorial is about as despicable as it's possible to get.
"I would ask the local community to come forward with any information they may have on those responsible so we can ensure they are brought to justice."