Met Police detectives are probing the abduction and sexual assault of two women who were snatched separately on Thursday.
The first was taken shortly after midnight from a street in Chingford, and the second around 12 hours later at 12.15pm from a street in Edgware.
The suspect drove the women to a hotel and attempted to book a room at around 1pm, but left when this was unavailable.
Both women escaped after a struggle in Osborne Road, Watford, at about 2.30pm.
CCTV pictures have now been released of a man police wish to speak to over the attacks as an arrest is made linked to the case.
“I would ask everyone to take a good look at his image – does this man look familiar?”
Detective Chief Inspector Katherine Goodwin
Police describe the suspect as a white man of muscular build, in his late 20s or early 30s.
He has a bald head or shaved blond hair and a light-coloured short beard.
The suspect is described as having a distinctive tattoo of the name Bobbie on his stomach.
And the car he was driving is believed to be a silver or grey Ford S-Max people carrier, with false registration plates.
Detective Chief Inspector Katherine Goodwin, leading the investigation, said the women were left traumatised by the random but linked attacks.
She said: “Our investigation into these appalling crimes is making good process and my team continue to work extremely hard, but we urgently need the help of the public to identify and trace this man.
“I would ask everyone to take a good look at his image – does this man look familiar?
“We believe he travelled around north London and Hertfordshire in his car from the early hours of Thursday and he may have come into contact with other members of the public.”
She added: ”Equally he may have abandoned his car somewhere – if an unfamiliar car of this description is now parked on your street, call police straight away.
“We would ask anyone with any information to contact us immediately.”
A CCTV still of a car believed to be a silver or grey Ford S-Max people carrier has also been released.
A 33-year-old man has been arrested on suspicion of conspiracy to rape.
The hunt for the rapist continues.