Neil Fonseca has confessed to killing his wife and sons, said Calcutta police officers who talked to him briefly twice in the past week.

"Neil Fonseca has confessed to the crime he has been accused of. He said he had killed his wife first and then his twin sons. We talked to him on Tuesday and Wednesday last week," joint commissioner (crime) Debasish Boral said on Tuesday.

"There has been no doubt since Day One that the three were killed. Now that Neil Fonseca has admitted to the crime, he will be charged with murder."

The 49-year-old interior decorator had allegedly used a newly bought dumbbell to smash the skulls of wife Jessica, 43, and the 16-year-old sons - Darren and Joshua - in their rented Palm Avenue flat early on January 16.

Neil had suffered a deep wound on the throat.

Neil has apparently told the investigators that he lost his cool when Jessica fought with him over an old relationship. The sleuths, however, suspect old debts might have been the cause of the three murders.

The police believe the wound on his throat was self-inflicted but what is still unclear is whether Neil wanted to commit suicide or injured himself to pose as a victim and mislead the police.

Jessica and the children were found dead in the bedroom they had been sharing with Neil.

Hours after the crime, Neil had apparently told the police that he had gone to the toilet and on returning found one of the sons lying still and the other being hit by Jessica by a heavy object.

He had said he couldn't control himself on seeing his wife's violent act and attacked her with a knife, at which she retaliated with a blade. In the scuffle, Jessica fell and banged her head against the bed and died. He tried to commit suicide after that.

Since January 16 Neil has been in a nursing home, where he has undergone surgery to fix an injury on the windpipe. The nursing home authorities said he was still having difficulty speaking.

"Whenever he is trying to speak, a wheezing sound is coming out. The police spoke to him for less than five minutes on both occasions," a nursing home official said.

A tracheotomy - an incision made in the windpipe - was conducted to facilitate breathing.

"The tube inserted through the incision is still there. We have reduced the width of the tube as the wound has healed to some extent. He complained of breathlessness when doctors tried to remove the tube," the official said.

Neil is on normal diet.

"He is otherwise doing well. He sometimes walks in the intensive care unit. He will be out of danger if he is found fine at least three days after the removal of the tube," the official said.

The doctors at the nursing home, he said, had declined to comment whether the wound on the throat was self-inflicted. "Only forensic doctors are qualified to say that," he said.