PARKLAND, Fla. – The State Attorney's Office released video Wednesday of the interrogation of Parkland school shooting gunman Nikolas Cruz.

Cruz was wearing a hospital gown as he was questioned for hours about the Feb. 14 shooting at Marjory Stoneman Douglas High School that left 17 people dead and 17 others injured.

He appeared calm and emotionless most of the time in front of the detective, and at other moments, when the detective left the room, he sat with his face in his hands, cried and bit his arms.

Local 10 News reporter Ian Margol spoke to Ryan Petty after the footage was released. Petty's daughter, Alaina, was among those killed in the freshman building.

"It's painful. I don't like to think about that day, to be honest. But if we're going to figure out how to stop this, we've got to try to understand it," Petty said. "I mean, it's clear to me we've got a sick individual that I think at the time was coming to grips with what he had just done."

Andrew Pollack, whose daughter Meadow was also killed in the shooting, spoke to Fox News about what he called a "bogus confession."

Bogus confession. Clearly pre-meditated with plans recorded and broadcasted to the world ahead of time on multiple occasions and in multiple venues. He begged for someone to stop him. #FixIt @FoxNews https://t.co/ndzC87mKka — Andrew Pollack (@AndrewPollackFL) August 8, 2018

The footage's release comes a couple days after prosecutors released a 217-page transcript of the interview with Broward Sheriff's Office Detective John Curcio.

Cruz told Curcio that he had spent about $4,000 on three shotguns and three rifles at a store and had done so legally.

The details about Cruz's calculated strategy to kill as many students as he could were not released.

However, Cruz did say his bad side, "the demon," had considered going to a park to shoot at people three weeks before he walked into a building at the school and killed 17 people and wounded 17 others.

READ TRANSCRIPT - Full transcript of Nickolas Cruz's statement

"I hear demons ... a voice, demon voice," Cruz, 19, said.

He also said that he had abused Xanax, because it made the demon go away. He said he used marijuana to silence the voices and alcohol to try to kill himself, according to the transcript.

Cruz also told Curcio that he wanted to talk to a psychologist.

"To find out what's wrong with me ... What the f -- is wrong with me?"

Cruz said there was an evil male voice that had ordered him to burn, kill and destroy for years.

When Curcio asked Cruz if he wanted cold water, Cruz said, "I don't deserve it." When Curcio left the room to get the water, Cruz could be seen in the video crying.

He pointed two fingers at his head at one point and said: "Just kill me. Just f--- ing kill me. F---!"

Curcio left Cruz alone in the interrogation room a short time later after asking Cruz if he wanted him to call someone from Cruz's cellphone to let him know where he was.

After thinking for a bit, Cruz asked Curcio to call someone named Rob, who he said knew his parents and who had known him since he was younger.

Once the door closed, Cruz picked up something on the floor and began scratching his right arm with it.

"We're seeing someone who, unfortunately, fits the profile of school shooters in our country -- serious mental health problems, depressed. He was engaging in an attempt at self-injury. Cutting is generally cutting, scratching, not letting wounds heal," Dr. Scott Poland, a psychology professor at Nova Southeastern University, said.

Cruz later told the detective that he had used a pellet gun to kill birds and a chicken. He said the voice told him to buy an AR-15 because it was "cool looking" and he wanted "to feel safe."

While he was working at the Dollar Store, Cruz said he heard the voice telling him to hurt people.

"The voice is, is in me ... To me, it's me and then my bad side ... It's a voice. The voice is in here and then it's me, it's just regular me, just trying to be a good person," Cruz said, pointing to his head.

Cruz also added he hears "the voice" more at night.

"There is one half that's a good and then the bad," Cruz said.

He said the voice made him feel less alone and even chose some of the music that he listened to including "Panzermensch," a metal song in German.

"I have someone in my head who I can talk to about it ... to have somebody ... because I have no one," Cruz said.

Cruz also said that when he didn't follow orders, the voice would tell him to hurt himself. He said he would regularly engage in non-suicidal self-injury. Before the shooting, he said, he had been fishing at a lake and had used a knife to scratch his arms.

Cruz said he wanted to be a U.S. Army Ranger, but he had failed the aptitude test. He said he thought his biological father was in the Marines, but he had never met him or made attempts to find his biological parents.

"I am stupid," Cruz said, also adding that he was a "coward."

Cruz said that when his mother was alive she was emotionally abusive and said he was crazy, stupid, and worthless. He also said his brother would also engage in name calling.

"I don't know if he cares about me or not ... I feel like the voice cares more about me than my brother," Cruz said.

Cruz said a girl, who was a student at Marjory Stoneman Douglas High School, was the love of his life. When he and a boy she had been talking to got in a fight, Cruz said he was embarrassed that the boy had overpowered him.

Cruz also said he didn't go out with other girls because he "scared them."

When Curcio left the interrogation room for the second time, Cruz talked to himself.

"I want to die. At the end you are nothing but worthless s---t, dude," Cruz said. "You deserve to die because you are f---ing worthless."

Curcio gave Cruz water, food and tried to appear compassionate. But when Curcio told Cruz that he didn't believe the demonic voice was real, Cruz stopped talking and asked him for an attorney. Curcio said he had to handcuff him to prevent him from hurting himself.

Curcio also allowed Cruz to meet with his younger brother, Zachary Cruz, who quickly told him people thought he was a monster.

Zachary Cruz also said he had a bad feeling and had made attempts to reach his brother through social media and text messaging before the school shooting.

"I know you probably felt like you had nobody but I care about you," Zachary Cruz said. "I literally would pull my heart out for you. I know I make it seem like I didn't care about you at all. I know I made it seem like when we were growing up that I hated you ... but truth is ... I didn't want to look weak. I love you with all my heart."

Nikolas Cruz hugged his brother. The two agreed: "Mom would cry." Zachary Cruz said he felt guilty. He begged his brother not to commit suicide and to seek God.

"I wish I could have prevented this ... this is a big part of, like, my fault also because, you know, I grew up ... I am sorry that I grew up being a dumb jerk to you and made fun of you and didn't want you to hang out with my friends ... we do different stuff. That's why we, I wasn't always there," Zachary Cruz said. "You know, I like to skate. You like to -- guns. Just, you like guns. That's all I knew."

Poland said the loss of Nikolas Cruz's parents and seeing his brother likely helped him "recognize the enormity of the horrific act that he has committed."