BOSTON -- After saying he would fight extradition to the U.S. to face charges he murdered his wife and baby, Neil Entwistle told a judge in a London courtroom Friday that he would voluntarily return to Massachusetts as soon as possible.

Had Entwistle fought extradition, it would have created a lengthy legal battle that could have taken months. He will now likely be arraigned in Framingham District Court in Massachusetts, possibly as early as next week.

As he left the Bow Street Magistrates Court he mouthed the words to his father, Cliff Entwistle, "Don't worry, Dad. I'm OK."

The British judge asked Entwistle if he was certain he wanted to waive extradition hearings, because his decision would be irrevocable and Entwistle said yes.

Entwistle, 27, was arrested at a London subway stop Thursday as he went to visit a friend. He's facing two charges of murder in the deaths of his wife Rachel, 27, and his 9-month-old baby, Lillian on Jan. 20.

The Middlesex County District Attorney's office said Entwistle had serious financial problems and he may have contemplated comitting a murder-suicide when he allegedly shot his wife and daughter as they lay in bed in their rented Hopkinton, Mass., home. He had reportedly looked for tips on the Internet on how to commit suicide.

Prosecutors said they believe Entwistle used a .22-caliber handgun that belonged to his father-in-law, then returned the gun to his in-laws Carver, Mass., home before boarding a plane to England.