When is a gunshot worth investigating?

The FBI is investigating whether a man who was shot in the chest was killed by a police officer, but the man’s family is not taking the probe seriously.

Authorities have not released a cause of death.

The man was shot around 11:30 p.m.

Sunday in the 600 block of West 23rd Street in the South Bronx.

The man’s mother, Jacqueline Lueffler, said she received a phone call from a friend about 8:45 p.g. saying that her son was shot, and that police officers had been on their way to their home in the 400 block of East 34th Street.

Luefflers mother said the police officers arrived on the scene, but that the man did not make any statements and that he did not tell them where he was going or who he was with.

The police officers, who had not been identified, left the scene and did not return Luefler’s call.

She did not know the man, but said he was white, in his 20s, with a black mustache.

She said her son had lived with her for about two years and worked as a cleaner.

The NYPD has a policy against releasing the identity of people shot in line of duty.

Luz Luefele, a spokeswoman for the New York Police Department, said the department does not release the name of people who are shot by police because they are under investigation.

Luingfer said it is not clear whether the man was under arrest at the time of the shooting.

Police said they responded to the home on an anonymous call and that they did not receive any additional information from the home.

The department said it did not release any other details.ABC News’ Michael LaBolt contributed to this report.