RICHMOND, Va. (AP) — The family of a young, black Virginia man who was fatally shot by police while naked and unarmed said the release of body-camera footage answered some of their questions about what happened but raised even more.

The video made public Friday shows Marcus-David Peters emerge naked from a car and dash onto Interstate 95 in Richmond, where he flails erratically before running toward the officer while shouting threats. The officer deploys a stun gun before shooting Peters twice.

Peters' sister, Princess Blanding, said at a press conference that her brother was clearly distressed and in need of help. She asked why the officer engaged with her brother after he noted that Peters seemed "mentally unstable" and why the officer told others at the scene further lethal force might be necessary after Peters was already on the ground, fatally wounded.

"Furthermore, this entire situation really has me wondering: Who are police trained to help? Who are they serving and protecting? Themselves?" said Blanding, who saw the footage along with other family members earlier in the week.

Peters' shooting, which took place along a busy stretch of Interstate 95, remains under investigation. Police Chief Alfred Durham, who spoke at a press conference Friday and released the video, asked the community for patience.

"Let the investigation take its course, please," Durham said.

The confrontation began May 14 after police say Peters made a stop a landmark downtown hotel where he worked part time as a security guard. Surveillance video shows him arriving clothed and leaving naked.

A short distance from the hotel, an officer saw Peters strike another vehicle with his sedan and flee, according to police. The body-camera video picks up with Peters' car in a brush-filled area next to an interstate ramp.

The officer, whom police have identified as Michael Nyantakyi, a 10-year veteran of the force who is also black, is seen with his handgun trained on the vehicle as he first approaches and orders Peters to stay in the car.

"Male seems to be mentally unstable as we speak," Nyantakyi says.

Peters exits the vehicle and dashes onto the interstate filled with rush-hour traffic, where a vehicle strikes him, the video shows. Peters then lies in the roadway, rolling back and forth and swinging his limbs.

Blanding said Friday that the behavior the video depicted was totally out of character for her brother, a teacher who graduated with honors from Virginia Commonwealth University in 2016. She has said her brother had no known mental health issues.

As Peters flails in the roadway, Nyantakyi is seen standing a short distance away with a stun gun drawn.

Peters then approaches the officer, slowly at first, and tells him, "Put that Taser down or I'll kill you."

Nyantakyi fires the stun gun as Peters continues to advance. Peters then runs toward the officer, and the video becomes shaky and more difficult to see. Two gunshots are heard.

The police chief played the video in slow motion for reporters and narrated as it ran. Nyantakyi shot Peters twice in the abdomen after deploying the stun gun, only one prong of which attached, Durham said.

Durham said they are investigating whether the stun gun was effective at all.

Peters stumbles and then walks away after being shot. The video shows him on the ground a short distance away soon afterward.

As arriving officers approach Peters to render aid, Nyantakyi, who is breathing heavily, cursing and has blood on his bands, tells them they'll need a stun gun and "probably more lethal force."

No other officers used a stun gun or lethal force. Peters died later at a hospital.

Nyantakyi remains on paid administrative leave while the investigation that will involve an autopsy and toxicology report continues, Durham said.

When the investigation is complete, police will forward the findings to the commonwealth's attorney's office, which will determine if the use of force was justified.

The chief emphasized that he understood the impact the incident has had on Peters' family and the community.

"I only wish we could have helped Mr. Peters," Durham said. "Unfortunately, we could not help him that day. For that, I'm truly sorry."

But Blanding, who spoke after the chief's press conference, said Durham had portrayed the officer's actions as reasonable.

"Nothing justifies Marcus not being here," she said.

Peters' family has planned a community rally Saturday that will be followed by a march the next weekend.

Blanding said she wants to see justice for her brother, whose death she said is part of a larger problem in the United States with how police interact with black people.

"As a black person, how do we know if we are in need of help that it will not result in death? ... It's wrong, and it's a tragedy, and something has to change," she said.