Veteran police officer in Des Moines, Iowa, shoots unarmed Ryan Bolinger through car window

Bolinger was unarmed at the time he was killed, and had no previous criminal record

The officer shot Bolinger through her car window (Sean Gallup/Getty Images)

A police officer in Des Moines, Iowa, shot an unarmed man dead on Tuesday evening, after he got out his vehicle and started "walking with a purpose" towards her car.

Police officer Vanessa Miller, who has seven years' experience, shot 28-year-old Ryan Keith Bolinger, after he led her and Ian Lawler, another senior officer, on a slow chase through the city streets.

Sergeant Jason Halifax of Des Moines Police told a press conference that Bolinger pulled up next to Lawler's police car, as it was parked off the road following a normal traffic stop just after 10PM on Tuesday night.

Halifax said that Bolinger pulled up so close to the police car that Lawler could not open the door. Bolinger then got out of his car and started "acting erratically".

He said: "It's been described as almost dancing in the street," but added "I don't want it to be construed that he's doing a waltz in the middle of Merle Hay Road."

The shooting occurred on Merle Hay Road, in the north western part of Des Moines (Steve Pope/Getty Images)

Bolinger got back in his car, and the officers pursued him in a low-speed chase of around 35 miles per hour. The officers said in public police radio transmissions that Bolinger was "weaving all over", and Lawler said he suspected that Bolinger may have been drunk, or mentally ill.

Bolinger made a U-turn and stopped abruptly, and Lawler stopped his car in front, to stop him continuing. Miller stopped behind Bolinger's car.

Shortly after, Halifax said Bolinger got out of his car and started "walking with purpose" towards Miller's car, making "a very quick advance". When he was close, she fired a single shot at him, the bullet shattering her closed driver's side window and hitting him in the torso.

The Des Moines Register reported that Bolinger had no criminal record and was unarmed when he was killed.

Police have launched an investigation into the cause of the incident. An autopsy will reveal whether Bolinger had drugs or alcohol in his system. Halifax also said there's a possibility Bolinger could have been deliberately provoking police as part of a 'suicide by cop' attempt.

According to guidelines, Des Moines police are allowed to shoot when they believe it is necessary to protect themselves or others, or when ordered to do so by a commanding officer.

They may also use their weapons in the course of arresting someone who has threatened to use, or used, deadly force, but only if all other methods of stopping the suspect have been exhausted.

Halifax said: "The use of deadly force can take many forms... there's not a hard, fast, 'this is when you shoot and this is when you don't'".

Halifax said that Bolinger walked towards Miller's car, but it is not known whether he threatened her, as audio recordings from the scene will not be released until after the investigation.

Police dashboard cameras were recording, but did not capture the shooting, which occurred to the side of the car. Body cameras may have provided a video record, but the Des Moines police department are still in the process of purchasing them.

A single protester arrived at the press conference, protesting against police violence in the USA. A string of killings of unarmed people by police have made headlines in the past year, along with protests and riots across the country.