A grand jury returned a first-degree murder indictment Wednesday against Ryan D. Petersen in last month's fatal shooting of a law clerk above W.A. Frost & Company in St. Paul.

The indictment is likely to escalate an already tense battle between prosecutor Rick Dusterhoft and defense attorney Gary Wolf, who butted heads Friday when Petersen tried and failed to enter a guilty plea to the original charge filed against him — second-degree murder with intent.

The indictment upgrades the original count to first-degree murder, which is punishable by life in prison, and also adds one count each of second-degree murder with intent and possession of a firearm by an ineligible person.

Petersen, 37, of St. Paul, is charged with shooting Chase Passauer, 23, of Minneapolis, six times in the stomach on April 7 at North Star Criminal Defense, on the second floor of the Dacotah Building in the Cathedral Hill neighborhood.

Petersen had fired one of the firm's attorneys that day, and had shown up at the office when he couldn't reach the attorney by phone. Passauer was the only person in the office.

Petersen tried to plead guilty last week, but Dusterhoft had produced an amended criminal complaint with the three counts that the grand jury approved Wednesday.

Dusterhoft argued that Petersen couldn't plead because he hadn't had a hearing on the new charges.

Wolf argued last week that the hearing was on the original count, and was the appropriate time to enter a guilty plea.

Ramsey County District Judge Gary Bastian rejected Petersen's guilty plea.

Wolf has said that he would ask a judge to dismiss a first-degree murder indictment, and would appeal to the state Supreme Court if necessary.

A grand jury meets in secret, and at least 12 of its 23 members must agree to return an indictment.

Petersen is scheduled to appear in court at 1:20 p.m. Thursday on the new charges.

Chao Xiong • 612-270-4708

Twitter: @ChaoStrib