A British aristocrat and her sex offender partner have been arrested after disappearing along with their baby, U.K. authorities announced Tuesday, though their infant has still not been located. Constance Marten, 35, and Mark Gordon, 48, were detained on Monday night after weeks on the run when a member of the public reported a sighting of the couple to law enforcement, Scotland Yard said in a news release. The pair were arrested on suspicion of child neglect after going off-grid days after their baby was believed to have been born in January. Detective Superintendent Lewis Basford said the search is “now all about that baby,” the BBC reports. Speaking to The Telegraph, Basford added: “I think, we’ve got to keep the hope that maybe they have allowed somebody else to care for the baby who thinks they are doing some good on behalf of the couple but as we know, as the temperature drops and the longer the baby goes without parents the risks are high.”