White Plains Public Safety Commissioner David Chong said he was not surprised by the lawsuit.

"We were notified very early on they were going to sue us," he said.

Chamberlain's lawyers had first said on May 3 that they intended to file a suit.

That was the same day that Westchester County District Attorney Janet DiFiore announced that a county grand jury had voted not to indict White Plains police Officer Anthony Carelli in the Nov. 19 shooting of Chamberlain Sr.

The police account of the incident is that Carelli shot Chamberlain as Chamberlain advanced toward police Sgt. Keith Martin with a knife. According to the police account, Carelli believed that Martin's life was in danger.

The shooting followed a two-hour standoff at Chamberlain's apartment door in the Winbrook Public Housing complex on South Lexington Avenue. Police went to the apartment after Chamberlain accidentally activated a medical alert bracelet that he was wearing. That triggered a call to police and paramedics.

Police said Chamberlain menaced them with a knife and meat cleaver as they used a master key to open the door to the apartment and subsequently -- upon encountering a chain lock -- removed the door from its hinges.

Carelli, who is white and a member of the police's elite Neighborhood Conditions Unit, shot Chamberlain, an African-American former Marine, only after cops first fired bean bags and then used a stun gun to try to stop his advance, police said.

Family members and their lawyers have complained that police used a racial slur during the incident, more than once. Police officials with access to audio and video recordings of the incident have denied there was any repetition of a racial slur, but have not denied a slur was used once.

The day after DiFiore announced the grand jury's findings, Manhattan U.S. Attorney Preet Bharara said his office would review the case to determine whether to open a federal criminal civil rights investigation. Kenneth Chamberlain Jr. and his lawyers met with officials from Bharara's office last week.

Family lawyer Randolph McLaughlin has said the White Plains police force -- specifically the Neighborhood Conditions Unit -- has a "pattern and practice of violating the civil rights of minorities and people of color."

Chong has said a review of the unit -- and possible changes to it -- would be part of an internal investigation into the department's handling of the Chamberlain incident.

Chong said the filing of the lawsuit would probably delay the public release of any information from the internal probe, which he said is not yet finished.