Updated

The FBI has closed its investigation into the 1997 murder of rap star Notorious B.I.G. (search), abandoning the theory that a rogue police officer may have been involved in the slaying.

The case was closed after federal prosecutors reviewed the evidence and concluded there was no basis for prosecution, Louis J. Caprino Jr., acting head of the criminal division of the FBI's Los Angeles office, said in Friday's editions of the Los Angeles Times.

Notorious B.I.G., whose real name was Christopher Wallace, was shot to death in March 1997 in front of hundreds of witnesses as he left a music industry party in Los Angeles.

Investigators have pursued various theories, including one that the killing, and that of rap star Tupac Shakur (search) in Las Vegas the year before, was the result of a feud between hip hop figures from the East and West coasts.

Shakur was the biggest West Coast hip hop star of his time, and he regularly exchanged insults and threats with Notorious B.I.G., his East Coast counterpart.

The FBI had also spent 18 months investigating the possibility that a rogue Los Angeles police officer working with rap mogul Marion "Suge" Knight had orchestrated Notorious B.I.G.'s killing. Knight, whose Death Row Records (search) was Shakur's label, has denied any involvement.

Investigators had said the officer, David Mack, owned a car matching the description of one seen speeding from the murder scene. A witness had also placed him at the scene hours before the murder.

However, other information gathered by investigators did not support the theory and detectives turned their attention elsewhere. Mack, who has since been imprisoned for robbing a bank, has denied any involvement in the killing.

FBI officials abandoned the probe in January after learning the lead agent on the case had talked with lawyers for Notorious B.I.G.'s mother, who is suing the Los Angeles Police Department for allegedly covering up police involvement in her son's slaying.

Voletta Wallace's suit, which seeks unspecified damages, is scheduled to go to trial April 12 in federal court in Los Angeles.

FBI officials said the lawsuit had nothing to do with the decision to end the investigation.