A veteran police officer shot and killed an unarmed man this week in Des Moines, Iowa, after firing through the rolled-up window of her patrol car. Police say the man, identified as 28-year-old Ryan Keith Bolinger, “walked with purpose” toward officer Vanessa Miller’s vehicle when she fired the fatal shot.

According to police, the incident began on Tuesday night when Bolinger pulled up his Lincoln sedan to a Des Moines police patrol car helping to make an unrelated traffic stop of another vehicle. Bolinger was allegedly so close to the pullover that the officer inside could not open his door.

In a press conference on Wednesday, Des Moines police sergeant Jason Halifax said Bolinger then got out of his car and began “dancing in the street or making unusual movements in the street”.

Halifax said that Bolinger then got back into his vehicle and led police on a low-speed chase before making a U-turn, giving officers an opportunity to block his path with their patrol cars.

It was at this point, Halifax said, that Bolinger got out of his Lincoln and rushed toward the officer’s vehicle. Officer Miller, a seven-year veteran, fired one shot at Bolinger’s torso, who died on the scene.

No weapons were found on or near Bolinger’s body.

Halifax told the Guardian on Thursday that it was not Bolinger’s rapid movement toward the patrol car by itself that prompted officer Miller to fire. But he would not elaborate on the specific reason, citing the ongoing investigation.

“She obviously felt something,” Halifax said, “and it involved what she was perceiving at the time, but that will be up to the grand jury to hear next.”

Neither officer Miller or any of the other officers involved were wearing a body camera.

The investigation is still pending, as are results of a toxicology report. A phone number listed for Bolinger’s family was disconnected.