"Urgent search" for infant after U.K. couple arrested following a month living off-grid

London — A woman with reported links to Britain's royal family and her convicted sex-offender boyfriend, who have been missing with the woman's newborn baby for over a month, were arrested by police in England for child neglect Monday night, but their infant was not with them.

"The baby is still missing and an urgent search operation is taking place in the area," Sussex Police said in a statement early Tuesday.

Constance Marten, 35, whose father served as a page to the late Queen Elizabeth II, according to the Sun Newspaper, and Mark Gordon, 48, who reportedly served 20 years in prison in the U.S. for rape and battery committed when he was 14, disappeared on January 5 shortly after Marten gave birth, Greater Manchester Police said.