John Hartless, from Liverpool, is wanted by police after a woman reported she had been sexually assaulted at an in Skelmersdale in February 2021.
The 73-year-old is described as white, 6ft tall, of heavy build with grey hair. He has limited mobility, the force added.
He has links to Dorset, Sussex, Hampshire, Merseyside, North Wales and Cheshire.
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DC Michael Feeley, of Ormskirk Police, said: "Hartless is wanted in connection with a serious offence and we would appeal to anyone with information about his whereabouts to come forward.
"I would also urge Hartless, if he sees this appeal, to come forward and speak to police immediately."
Anyone with information can call 101 or email [email protected] quoting log 0287 of February 17.
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