A man originally charged with 10 counts of second-degree assault and terroristic threats after he threw a 50-pound sandbag off the John Ireland Bridge onto Interstate 94 during the Republican National Convention pleaded guilty Monday in Ramsey County District Court.

David T. Mahoney, 24, who has no permanent address, pleaded guilty to one count of second-degree assault. The plea agreement calls for him to serve 90 days in jail after he is sentenced July 9 by District Judge Paulette Flynn.

According to the criminal complaint, Mahoney picked up a sandbag holding down a traffic sign and tossed it over the railing onto the freeway below. The sandbag did not hit a vehicle, but Mahoney was directing other protesters to throw sandbags when they were chased away by a squad car.

Investigators were able to identify Mahoney through a tattoo on his back, noticeable on surveillance photos that authorities took when the sandbag was tossed.

The bridge went over one of the primary routes that buses used to take delegates to the convention at the Xcel Energy Center in St. Paul.

PAT PHEIFER