By Fiona Ortiz

CHICAGO (Reuters) - Chicago police on Wednesday arrested a man suspected of murder, shortly after he left his own news conference where he announced he was suing the city for $15 million over an incident two years ago when he alleged being shot seven times by a police officer.

Dominiq Greer was arrested after he and his attorney, Eugene Hollander, announced the federal lawsuit, which alleges excessive force by police who shot Greer on July 4, 2014, as he ran from them, the lawyer later said by telephone.

The Chicago police department is under federal investigation into whether it has a pattern of excessive use of force. The city has paid more than $500 million in police misconduct payments since 2004, according to Chicago's law department.

The federal probe was launched after protests last year following the belated release of a 2014 video in which a white police officer shoots a black teenager 16 times, killing him.

Greer was arrested on an outstanding warrant from a shooting last month, Chicago Police spokesman Anthony Guglielmi said in a statement that did not mention the lawsuit. He did not immediately respond to questions about the lawsuit.

Guglielmi said Kevin Larry, 22, was found dead of an apparent gunshot wound inside an apartment on May 27. He said others were in the apartment at the time, but Greer was singled out as the suspected shooter.

Guglielmi said Chicago police went to Hollander's downtown office on Wednesday after learning of the press conference and arrested Greer without incident.

At the news conference, Hollander said he showed a video depicting Greer being shot three times before he got up and ran and was then shot four more times. Greer was hospitalized in critical condition with multiple injuries, the lawsuit says.

Hollander said that Greer acknowledges he was carrying an illegally purchased gun on the night he was shot, and he threw the gun away as he ran away from police.

The lawsuit says Greer fled because he was fearful of being arrested, adding there was no reason for police to fear he would harm them because he was running away. The lawsuit names two police officers, one who fired the shots and one who the lawsuit claims could have prevented the shooting.

Hollander said the civil lawsuit would continue its course.

"The lawsuit's got nothing to do with any pending criminal charges. If it's a pending charge, the state's going to have to prove their case," he said.

(Editing by Curtis Skinner and Matthew Lewis)