As police investigate the shooting of a man by an undercover officer in Brooklyn Saturday night, the dead man's family is demanding answers.

Police say a narcotics officer on a drug operation was sitting on a stoop on Lafayette Street in Clinton Hill Saturday night.

They say Shem Walker, 49, came out of his home, told the officer to leave, saying "Get out or I'll move you myself," and attacked after the officer refused to move.

Police say the two struggled over the officer's gun before it went off twice, hitting Walker once in the chest. He was pronounced dead at Brooklyn hospital.

The officer suffered a head injury.

But Walker's family and their supporters are disputing the New York City Police Department's account, saying the 15-year Army veteran had just come outside on his mother's doorstep to smoke.

"The fact that an undercover officer did not leave [Walker's] stoop, his property, and the fact that there was an altercation, at a time when the family was sitting by the window and didn't hear anyone shout 'police,' raises some serious questions in my mind and in the mind of my constituents," said City Councilwoman Letitia James.

Police say they have witnesses that heard the undercover officers identify themselves.

They say the officer that pulled the trigger is a seven-year veteran who has been undercover for 26 months and that he has never been involved in any other shootings.

Family members say that although on parole for a drug conviction in Pennsylvania, Walker planned to make a permanent home in Brooklyn to care for his disabled mother. They say he took his mother to church every Sunday.

"The Bible says honor your parents and your days will be long," said the Reverend Michael Baccus. "But this is not long enough. This is very, very tragic. "

"My father was a good person, a good person, and they took him away from me," said Shavone Walker.

Councilwoman James says she asked the police to look into the drug problem in the area, but it had nothing to with the Walkers or 370 Lafayette, and she wants an independent investigation into the shooting.