ST. LOUIS • A lawyer for the young child of a man killed by St. Louis police in December said today he will file a lawsuit alleging that officers shot him even though he was unarmed and pleading for his life.

Albert Watkins, the attorney, said he expects to file suit Monday in U.S. District Court.

A police spokeswoman confirmed today that the department has asked the FBI to look into the case at issue, the Dec. 20 death of 24-year-old Anthony Lamar Smith. The FBI confirmed that it was being done.

Christina Wilson, 31, Smith's pregnant girlfriend and mother of their 1-year-old daughter, told the Post-Dispatch at the time that she was on a cell phone call with him when he was shot.

"He was crying for help, " she said softly. "I could hear him moaning, ‘Oh, oh.'"

Watkins alleged that an officer, whose name he did not reveal,  planted a firearm on the dead man afterward.

The lawyer also claims the officer brandished what appeared to be an AK47 rifle at one point but did not fire it. Police policy requires officers to use only department weapons, which do not include that type.

Watkins said the claims are based in part on what Wilson heard during the call.

He also said that elements of the incident are backed up by a patrol car dashboard camera video, and possibly by an audio recording made by the ONSTAR motorist assist system, which turned on when Smith's car was involved in a collision during a police pursuit and an airbag deployed.

Police said at the time that Smith was a drug suspect who was shot after a mile-long chase that began with a suspected drug transaction near a Church's Chicken restaurant at Thekla Avenue and Riverview Boulevard.

Authorities said that when officers first approached Smith's car, he reached for something and drove toward one of them, so the other fired. The car continued to West Avenue Florissant and Acme Avenue, where the collision occurred.

Police said they again approached his vehicle, ordered him to show his hands and fired when he reached under the seat.

Officials said they found drugs and a gun in Smith's vehicle.

Court and prison records show that Smith faced theft, weapons and drug charges in the past and served prison time on at least some of them.

Wilson, who was engaged to marry Smith, told a reporter in December that she didn't believe the gun found with him was his, and suggested that he probably had been seen reaching for a cell phone.

Smith lived in the 4800 block of Page Boulevard.

Police were put on high alert after the incident, as graffiti appearing to threaten officers was painted on the same Church's restaurant.

Robert Patrick and Denise Hollinshed of the Post-Dispatch contributed to this report.