A man arrested over the abduction and rape of three women in and around London is being investigated for other attacks involving nine further victims.
Joseph McCann, 34, was arrested in Congleton, Cheshire, after two girls, aged 14, were abducted in the town.
He is being investigated over attacks in Cheshire, Manchester and Lancashire, on victims aged between 11 and 71.
Det Ch Insp Katherine Goodwin, of the Metropolitan Police, said the attacks were “grotesque and horrifying”.
The officer urged other victims to come forward and want to hear from anyone who had been approached by Mr McCann or in contact with him between February and May.
Mr McCann was found in a tree in Smithy Lane on Sunday evening and arrested after a stand-off with police negotiators.
He had been spotted in the town after two girls were forced into a car that afternoon.
Met detectives are now investigating him in connection with a number of other attacks earlier that day.
These include the false imprisonment of a woman in Haslingden, Lancashire, in which a teenage girl and a boy, 11, were raped and the abduction and rape of a 71-year-old in Bury, Manchester.
The suspect is also being investigated over the abduction of two 13-year-old boys and the abduction and sexual assault of a 13-year-old girl in Heywood, Manchester, at about 15:30 BST on Sunday.
Det Ch Insp Goodwin said the attacks were believed to have taken place between 21 April and 5 May.
“Detectives from the Met continue to lead on this investigation and are working very closely with policing counterparts where he is suspected to have carried out further offences,” she said.
Mr McCann was also wanted for questioning over the abduction and rape of a 21-year-old woman at knifepoint in Watford, Hertfordshire, in the early hours of 21 April.
The Met Police launched an appeal to find Mr McCann after two women in their 20s were snatched off streets in London and raped in a car in London on 25 April.