A reward of up to £5000 is being offered for information leading to the arrest and conviction of a man who carried out sex attacks on two women.
Charity Crimestoppers is offering the reward and information can be provided anonymously.
Police have a full DNA profile of the attacker and know he carried out both assaults.
In the first attack, a 19-year-old woman was assaulted after she got off a bus in Lanark Road West in Edinburgh shortly after midnight on Thursday, August 27, 2015, when a man approached her in the Newmills Road area and claimed he had a knife.
He then led her to a nearby field, where she was raped.
Earlier that month, on Wednesday, August 5, a 21-year-old woman was grabbed from behind and sexually assaulted in Craiglockhart Quadrant.
She had got off a bus in Colinton Road shortly before the attack, at about 10.30pm.
The man responsible had not been on either bus.
Crimestoppers national manager for Scotland, Angela Parker, said: “These victims have been through horrific ordeals which no one should ever have to endure.
“We should all be able to walk around in our community safely during the day or at night without fear, which is why our charity has put up this reward.
“We are appealing to anybody who may have information on this attacker to contact our charity, with the promise that you will remain completely and totally anonymous.
“We know the police are looking for somebody you’d least expect to commit such awful offences.
“Please cast your mind back to August 2015. Was there somebody in your life, a colleague, a friend or a family member who was acting in an unusual way for them at the time?
“The Edinburgh Fringe Festival was taking place and the Royal Edinburgh Military Tattoo’s theme was East Meets West, to mark the 75th anniversary of the Battle of Britain.”
She added: “People tell us how difficult it can be coming forward, but that our anonymity guarantee gives them the confidence to take action, safe in the knowledge that no one will ever know.
“You can call our UK Contact Centre which is open 24 hours a day on freephone 0800 555 111 or you can use our simple and secure anonymous online form at Crimestoppers-uk.org.”
Only information passed through either of these channels which leads to the arrest and conviction of the attacker will qualify for the reward, not information given directly to the police.