The family of a teen with autism who was forced to the ground by an Arizona cop mistaking his behavior for that of a drug user has called on police to better train officers for such situations while asking for an apology.

Connor Leible, 14, was playing with string when an officer with the Buckeye Police Department approached him in July.

“What are you doing?” the officer can be heard asking Connor on bodycam footage of the incident that has since been released.

The teen replies that he’s “stimming,” a self-stimulation technique that people with autism use to calm themselves, and that all he has in his hand is a string.

As he backs away, however, the officer responds.

“What? Stop walking away from me,” the police officer, who officials said is trained as a drug recognition expert, tells Connor.

Read: Non-Verbal Man with Autism Saves Baby's Life After Facebook Messaging Police

“You have any I.D. on you?” the cop asks.

“No,” Connor replies, and tries to walk away.

From there, the situation quickly escalated.

The bodycam footage shows the officer tackling Connor, who screams as he falls to the ground and is handcuffed.

“It was really hard to watch that," Connor’s mother, Danielle Leible, told CBS News. "That's my — that's my baby."

The incident left Connor with multiple cuts and bruises, as well as an ankle injury his mother said may need surgery.

“He pushed me down on the grass and he just hit me on the tree, and he tackled me and then he didn't stop,” the teen told CBS News.

His mother was unable to hold back tears as Connor explained how the ordeal affected him.

“It made me feel sad,” the teen said.

Read: Mom of Arrested 10-Year-Old With Autism: Nightmare Continued After Video Ended

The Buckeye Police Department’s internal investigation cleared the officer of any wrongdoing, finding there was no excessive use of force and determined the stop was reasonable, given his training as a drug recognition expert.

“I hope the family sees that we will learn from this incident,” Det. Tamela Skaggs told CBS News. “We are human and things are constantly evolving and changing, and it's almost impossible to know and understand every single little piece of every single disorder.”

Connor’s mother had issue with Skaggs’ reasoning, telling the television station: “They say, 'Nothing was wrong, he didn't do anything wrong, but we're going to make sure we handle it differently.’ Why would you need to handle it differently if everything was done correctly the first time?”

The Leible family said they sent a letter to the police department asking the officer for an apology, requesting that he participate in an autism-related community service project and asking that all officers receive more training.

The Buckeye Police Department told CBS News it has received the letter, but they said they are unsure when or if they will respond.

Watch: Video Shows Teachers Dragging 7-Year-Old Boy With Autism Across Floor