New Haven — Suspended cop Oscar Diaz who slammed on the brakes of the police transport van when Randy Cox was injured wants an unknown driver added as a defendant in the $100 million lawsuit filed against him, four other officers and the city, court documents show.

In a motion filed in the civil case, attorney James Tallberg said Diaz would not have needed to slam on the brakes if an unknown female driver hadn't gone a few feet past a stop sign as his client was approaching the intersection of Division and Mansfield streets while transporting Cox on June 19.

"As a result of the negligence of the operator of the unidentified vehicle, officer Diaz was forced to abruptly apply the transport van's brakes and sound the transport van's horn, to avoid colliding with the unidentified vehicle," Tallberg wrote in the court filing.

Tallberg did not return a phone call Monday seeking additional comment.

More than eight months since the incident, Cox can only move his left arm in a limited manner and turn his head, but he is otherwise paralyzed from the chest down and needs constant medical care, one of his attorneys said Monday.

"It's irresponsible that they are trying to point the finger at someone else," said Louis Rubano, one of several lawyers working with civil rights attorney Ben Crump to represent Cox in the lawsuit. "He was placed in handcuffs, but the van had no seatbelts. The officer was driving in excess of the speed limit and slammed on the brakes. Instead of responding to his pleas for help, the officer ignored them. Now the officer is trying to blame the driver and EMS."

The five officers named in the lawsuit, including Diaz. filed a motion on Jan. 7 seeking to blame Cox's injuries on EMS who responded to the police station, court documents said. The filing claims the two emergency medical technicians from American Medical Response of Connecticut failed to stabilize Cox and properly assess his injuries.

Video obtained by Hearst Connecticut Media Group from the New Haven Police Department shows the corner of Mansfield and Division streets when the incident occurred. The video, which is from a nearby business, appears to show an SUV stop before Diaz slammed on the brakes of a police van.

The video shows the SUV approaching the intersection from Mansfield Street and briefly stopping. No stop sign is visible in the footage. At that point, the police van cannot be seen in the video. The SUV moved forward a few feet before stopping again as the police van approached from Division Street, the footage shows.

Diaz slammed on the brakes at the intersection, claiming in police reports he was trying to avoid a collision with the other vehicle. Diaz was going 36 mph — 11 more than the speed limit — when he hit the brakes, state police said in the arrest warrants for the officers.

The SUV did not travel fully into the intersection until after Diaz had proceeded straight on Division Street, the footage shows.

Video from inside the vehicle shows Cox wedged awkwardly on the floor of the van after Diaz slammed on the brakes. The video shows Cox calling for help and saying he thought his neck was broken. Diaz stopped the van a short while later, but didn't wait for EMTs to arrive and continued to the police station where Cox was dragged out of the van by his feet as officers insisted he was drunk and uncooperative, body camera footage released by the city shows.

When he was finally brought to Yale New Haven Hospital, doctors determined Cox had broken his neck during the incident.

Diaz, Sgt. Betsy Segui and officers Ronald Pressley, Jocelyn Lavandier and Luis Rivera were suspended and later charged with reckless endangerment and cruelty to persons in connection with the incident. They have all pleaded not guilty to the charges. Cox's family filed a lawsuit in September seeking $100 million from the officers and the city for his ongoing care.

The attorneys for Cox and the city have been in negotiations to settle the case, but so far the discussions have not resulted in a resolution, Rubano said.

"This is your profession," Rubano said of the police. "This is the men and women of the New Haven Police Department failing to accept responsibility for their actions, which paralyzed a man from the chest down."

Staff writer Peter Yankowski contributed to this story.