David Michael Mattson-Fuller, 19, of Austin pleaded guilty on Wednesday in Mower County District Court to a charge of felony third-degree assault-substantial bodily harm as part of a plea agreement. He initially pleaded not guilty to the charge on Oct. 2.

Two charges of felony-second degree assault with a dangerous weapon will be dropped at the sentencing.

Mower County Jail staff responded to a fight between two inmates on Aug. 7 in a common area within the jail. An inmate said Mattson-Fuller started hitting him, so he grabbed Mattson-Fuller’s left leg and held it while trying to avoid fighting. The inmate said Mattson-Fuller punched and kicked him in the head and ribs and complained of severe pain on the left side of his torso. The inmate had bruising on his left rib area, scuffs on his elbows and “knots” on the back of his head.

The deputy who broke up the fight said he saw Mattson-Fuller on top of the inmate hitting him with his fists.

Surveillance footage showed Mattson-Fuller as the aggressor. The assault lasted approximately 19 seconds.

A review of Mattson-
Fuller’s criminal record shows prior convictions for assault, theft, criminal damage to property and making terroristic threats.

The sentencing date has yet to be determined.