A woman in her 60s sustained knee injuries as she was pushed over during an alleged sexual assault in Boston.
The incident happened at around 4.30am on October 7 when the victim was on her way to work, walking along Fydell Crescent.
Officers are appealing for information to help with their investigation.
It is believed the attack may have been witnessed and one member of the public stepped in to intervene, police said.
Police said: “It is vital that we speak to these people so they can assist with our enquiries.”
Anyone with information should contact police on 101 quoting reference number 177 of October 9.