MANKATO, Minn. (WCCO/AP) — A man arrested in a weekend assault that severely injured a former Minnesota State, Mankato, football player has been charged with two felony counts.

Police arrested 21-year-old Trevor Stenner Shelley on Monday, hours after they released surveillance video showing him running from the scene in downtown Mankato.

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Former Minnesota quarterback Philip Nelson is already charged with two counts of felony assault. A criminal complaint says Nelson kicked 24-year-old Isaac Dallas Kolstad in the head after Shelley punched Kolstad, knocking him to the ground.

Shelley has been charged with first- and third-degree assault, which carry maximum respective penalties of 20 and 5 years in prison upon conviction.

Nelson’s attorney has said his client was not the aggressor and that it’s not clear who caused Kolstad’s injuries.

The criminal complaint lists accounts from different bystanders. A girl who had been out drinking with Nelson and who, like Nelson, was under 21 said that he became enraged after a bouncer kissed her on the hand.

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A friend of the victim’s said Kolstad and Nelson were engaged in a “heated exchange,” but it was not clear to him whether the fight was actually about Kolstad. The friend said that as he was trying to diffuse the situation with Nelson, someone else knocked Kolstad down. At that point, Nelson pushed past him and kicked Kolstad in the head at least once, possibly twice.

Police said surveillance video shows Kolstad striking Nelson on the shoulder from behind while Nelson and the girl were talking with Kolstad’s friend. At that point, a male later identified as Shelley knocks Kolstad down with a punch to the head, investigators said.

Nelson said that he didn’t know the person who punched Kolstad, but officers saw that both Nelson and Shelley were friends on Facebook, and had both attended the same high school.

After being identified, Shelley informed police that he hadn’t struck Kolstad but, rather, that Kolstad had taken a swing at him.

Kolstad’s family said on its CaringBridge website that a surgery Kolstad had on Tuesday morning went well. He was still in critical condition.

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