LONDON — British police have arrested an aristocrat and her partner who have been sought for weeks, since they went missing with her newborn baby. The search for the child continues.

Constance Marten, Mark Gordon
Constance Marten, Mark Gordon (Metropolitan Police via AP) 

Constance Marten, 35, and her boyfriend Mark Gordon, 48, a convicted sex offender, had been on the run since the baby was born in early January.

London’s Metropolitan Police said in a statement that Marten and Gordon were arrested Monday in Brighton on suspicion of child neglect, then were “further arrested on suspicion of gross negligence manslaughter.”

The baby was not found with them and Detective Superintendent Lewis Basford said police had to “consider the possibility that the baby has come to harm.”

The child is thought to have been born in the couple’s car or on the roadside and received no medical attention at birth.

Marten, who was reportedly a drama student when she met Gordon, is from an aristocratic family that has a large inherited fortune, including a sprawling Dorset estate with a 400-year-old home used as a location for the 1996 movie of Jane Austen’s “Emma.”

Gordon served 20 years in prison in the United States after a juvenile conviction in Florida for kidnapping and sexual battery and was deported to England after his release, U.S. law enforcement officials said.

The search for the pair began on Jan. 5, after police inquiries identified them as being associated with a car that was found burning on a highway near Bolton. They had not remained at the scene.

Police used witness sightings and security camera footage to map their movements through various cities and towns.

On Jan. 7, they were seen in London, getting out of a taxi with their faces covered. They had a baby stroller with them. That day, they used cash to buy a two-person tent and two sleeping bags. Before leaving town, they discarded the stroller.

“Throughout this investigation our key priority has been finding the baby, and we remain committed to that,” Basford said in the statement Tuesday.

He said the arrest Monday followed a tip from a member of the public, and he appealed to residents of the area to report any information about where the couple may have slept.

In an audio appeal last month to his daughter, published by British news outlet The Independent, Napier Marten said Constance was “much, much loved, whatever the circumstances,” adding that the family was “deeply concerned” for her and her child’s welfare.

“Darling Constance, even though we remain estranged at the moment, I stand by, as I have always done and as the family has always done, to do whatever is necessary for your safe return to us.

“I beseech you to find a way to turn yourself and your wee one into the police as soon as possible so you and he or she can be protected.”