Baltimore police are investigating arrest shown in viral video

(CNN)Baltimore police say they're investigating the arrest of a man which was captured on video and went viral on social media.

The 45-second video posted on Twitter begins with two officers positioned over a man while he lays on his stomach on the sidewalk. The video does not show the interaction between the man and the officers before video recording began. One officer is on top of the man's upper back with his arm wrapped around his neck. He yells at the man to put his arms behind his back.
The man on the ground can be heard yelling, "You're choking me, sir! You're choking me." Two people are heard speaking with the officers during the arrest but are not in camera view.
Police said they've been investigating the incident since Monday, when the arrest occurred, though the video was brought to their attention Thursday.
"In all cases like this, we investigate the circumstances that led to the arrest and evaluate whether the arrest itself and the use of force are in compliance with the department's policies and procedures," said Matthew Jablow, spokesperson for the Baltimore Police Department.
Jablow identified the man being arrested as 23-year-old David Dixon.
His charges have since been dropped, the Baltimore state attorney's office said.
"Based on the review of the unreleased body worn camera footage, dismissal of the charges was warranted and further investigation has been initiated," said Zy Richardson, spokesperson for the Baltimore state attorney's office.
The dropped charges included felony drug possession, trespassing and resisting arrest for allegedly biting the officer, police said.
CNN has made multiple attempts to reach Dixon for comment. CNN has not been able to view the police body cam video and has not been able to contact the person who made the video posted on Twitter.
According to the police report obtained Friday by CNN, detectives were patrolling an area on West Lexington Street known as "an open air drug shop" when one of the detectives observed a man turn away from them and reach into the front of his waistband. Upon approach, the detective attempted to detain the man for trespassing by grabbing his jacket and felt what he suspected were heroin gel caps through the pocket, the report said.
The man resisted officers, the report states, and struck one officer in the face and abdomen area. Police used a stun gun on the man three times but he kept resisting, the report said. Detectives managed to get the man in a prone position and grab his hands, the report said, but the man bit one detective's hand. The detective responded by striking the man in the face with a fist before officers finally handcuffed him, the report said.
Police confiscated 32 gel caps of suspected heroin, 42 gel caps of a suspected cocaine, jugs containing a white rock substance and more than $1,000 cash, the police report said. The man received medical treatment for stun gun wounds and the officer was treated for the bite, the report says. The officer says in the report that his body camera became detached from his uniform as a result of the struggle between him and the man.
Baltimore City Council President Brandon Scott retweeted the video on Twitter, saying he immediately alerted Baltimore Police Commissioner Michael Harrison and that the incident is under investigation.
"In the short clip, the officer in the front is holding Mr. Davis in a chokehold position and appears to have used his Taser on the victim, as the device's probe cords are visibly released," Scott said in a statement. "These facts alone are cause enough for a thorough investigation into this incident."
At the end of November, Harrison released a new "use of force" policy for police officers. The 11-page document outlines core principles, definitions and a three-tier system that defines levels for intensity of force.
The Baltimore Fraternal Order of Police declined to comment.