BOSTON -- British police arrested Neil Entwistle, 27, in the slay case of his wife, Rachel, and daughter Lillian Entwistle.

The a mother and baby were found dead in the Entwistle's Hopkinton home Jan. 22.

Entwistle was arrested in by British authorities about 7 a.m. eastern time, at a British Subway station, according to Emily LaGrassa, a spokeswoman for the Middlesex County district attorney's office. He faces murder charges, which must be brought to a Massachusetts grand jury in a formal indictment.

London's Metropolitan Police said Entwistle was arrested on a provisional extradition warrant issued Wednesday evening.

The D.A. has been investigating the case ever since the Rachel, 27, and her 9-month-old baby were found shot to death in an upstairs bedroom of their home. Each died of a single gunshot wound, according to autopsy results released Tuesday. Rachel died from a gunshot wound to the head. Lillian was shot in the abdomen, but that bullet also entered her mother's torso.

Neil Entwistle, a British citizen, boarded a flight for England that same weekend and was staying with his parents in their Worksop, England home. He did not return for the funerals of his wife and child which were held Feb. 1 in Plymouth, Mass.

The couple, who met while Rachel Entwistle was studying abroad at York University in England, had only been married for three years. Their daughter Lillian was born last April.

Investigators had looked at the Entwistle's business dealings on the Internet, where they sold software and adult business opportunities on eBay.

Rachel Entwistle's family on the South Shore did not include Neil Entwistle in published funeral notices and issued a statement through a family spokesman.

"From the birth of Rachel's daughter, Lillian Rose Entwistle, last April, Rachel shared her greatest love -- that of being a mother. As the family continues to grieve, we also celebrate and are grateful for the time we had with Rachel and Lilly," family spokesman Joe Flaherty said said in a statement on behalf of Rachel's mother, Priscilla Matterazzo, stepfather Joseph Matterazzo, and Rachel's brother Jerome Souza.

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