A woman in her 50s was allegedly sexually assaulted by a man wearing glasses at a house in Alford.
Lincolnshire Police received a report at around 2pm on Sunday, February 9 of a man entering the house before the incident occurred.
The force released an image of a man on Friday, March 27, who they wish to identify in connection with the incident.
The man is described as white, in his late 40s or early 50s, and of an average build. He has short grey hair and is wearing glasses.
Police said at the time the incident was reported he was wearing a light coloured shirt and beige trousers.
Police did not specify whether the man in the image is a suspect or a witness.
Anyone who recognises the man, or that can assist with the investigation, should contact police on 101 or via email at [email protected] quoting incident 480 of February 9.
It can also be reported through the independent charity Crimestoppers anonymously on 0800 555 111.