A Chicago cop who fatally shot a mentally ill college student in December — as well as the teen’s unsuspecting neighbor — is now suing the dead teen’s family for $10 million, claiming the killings gave him “extreme emotional trauma.”

Officer Robert Rialmo filed the staggering suit Friday over his contested killing of 19-year-old Quintonio LeGrier, a Northern Illinois University sophomore. The officer also accidentally killed Bettie Jones, 55, who was standing nearby, according to police.

The slain student’s family immediately slammed the suit, which comes amid the exploding scandal over deadly, racially motivated police tactics in Chicago.

“After this coward shot a teenager in the back ... he has the temerity to sue him?” LeGrier’s family attorney, Basileios Foutris told the Chicago Tribune.

“That's a new low for the Chicago Police Department.”

Rialmo shot LeGrier six times on Dec. 26 after the teen made three calls to 911,making vague but distressed remarks about an “emergency” he said needed a police response. The gunfire erupted after LeGrier rushed at the officer while swinging a baseball bat, according to police, with one shot passing through the teen and striking his neighbor.

Rialmo’s suit says LeGrier “took a full swing” with the bat at Rialmo after the officer arrived at his home, just missing the cop’s head by a few inches. After Rialmo stepped back and LeGrier refused orders to drop the bat, the teen followed the officer outside and took another swing, forcing Rialmo to act in self-defense, the suit says.

“Rialmo reasonably believed that if he did not use deadly force against LeGrier, that LeGrier would kill him,” the suit says.

The two deaths that resulted from the fatal encounter will “continue to cause...extreme emotional trauma” to the officer, according to the suit, which asks for a “sum in excess of $10,000,000” for damages.

Rialmo’s suit contradicts the story given by LeGrier’s family in their wrongful death suit, which said the teen was inside his building and shot by the cop from the outside. The family’s suit also said LeGrier did nothing to threaten Rialmo or anyone else on the scene, and was not involved in any illegal activity at the time.

The suits come months into Chicago’s continuing crisis of police killing black men who are either unarmed or not presenting an immediate threat to officers. In many of the cases, including this one, the officer responsible for the death was white.

Protests over police tactics and alleged coverups led to the ousting of the Chicago's top cop last year, and calls for Mayor Rahm Emanuel to step down. The most infamous case — the death of Laquan McDonald, a black teenager who was shot by a white officer 16 times — led to the city settling with the teen’s family for $5 million.

Rialmo’s attorney accused LeGrier’s family of trying to ride the wave of city actions against cops.

“Ever since the McDonald payoff, people are treating officer-involved confrontations like a lottery ticket and they're waiting to cash it in,” Brodsky told the Tribune.

Chicago cop who shot teen sues family for $10 million - NY Daily News