A Chicago policeman who fatally shot a 19-year-old college student and accidentally killed a 55-year-old grandmother in the same incident has sued the teenager's estate, blaming him for prompting the shooting and causing the officer emotional distress.

Officer Robert Rialmo filed a countersuit on Friday against the estate of Quintonio LeGrier, a black college student, in state court in Chicago. The complaint accused LeGrier of attacking Rialmo with a baseball bat in late December, forcing him to use his gun to save his own life.

One of the bullets passed through LeGrier's arm and struck his neighbor, Bettie Jones, in the chest in what police have described as an accident. Jones was also black. Rialmo is a white officer.

“It's a new low. First you shoot and kill somebody and then you are going to try to sue them,” said Basileios Foutris, the attorney for the estate of LeGrier.

Foutris said he saw the lawsuit as an attempt to deflect attention from what the officer had done and was planning a legal response.

The shooting came during heightened tensions over the use of force by Chicago police against minorities. Protesters have called for Mayor Rahm Emanuel's resignation following several high-profile incidents, most notably a white police officer's fatal shooting of black teenager Laquan McDonald.

That killing, captured on video, led to first-degree murder charges against the officer, Jason Van Dyke.

The mayor has ousted his police superintendent in response and called for improved training for police officers. The U.S. Department of Justice has opened a civil rights investigation into the department.

Rialmo's counterclaim came in response to a lawsuit filed by LeGrier's family. Jones' family has also filed a lawsuit against Rialmo over the shooting.

Those lawsuits offer different accounts of the shooting. The LeGrier lawsuit alleges he posed no threat when Rialmo shot him, while the Jones lawsuit says Rialmo fired an indiscriminate “hail of bullets” in her general direction.

Joel Brodsky, a lawyer for Rialmo, said the officer was justified in firing his gun and blamed both LeGrier's and Jones' deaths on LeGrier’s actions.

“Facts are a stubborn thing,” Brodsky said, quoting U.S. founding father John Adams. ”This whole horrible event was the result of Quintonio LeGrier trying to take my client's head off with an aluminum baseball bat.”

The Associated Press