Federal prosecutors have dropped fraud charges against a Wayzata stockbroker for allegedly aiding a stock-manipulation scheme at oil-field services company Dakota Plains Holdings.

Nicholas Shermeta was charged in March with five counts of wire fraud in connection with Dakota Plains' initial public offering in 2012. Prosectors accused Shermeta of being an accomplice of Ryan Gilbertson, a co-founder of Dakota Plains, who was indicted on 11 counts of wire fraud.

On Friday, the U.S. attorney's office for the District of Minnesota dismissed the case against Shermeta with prejudice, meaning it's dismissed permanently. "Nick and his family are delighted to have the criminal charges behind him," said Chris Madel, Shermeta's attorney.

Shermeta has agreed to cooperate with prosecutors, including possibly testifying. The case is uncommon in that such cooperation agreements usually come with plea bargains, not outright dismissals.

Prosecutors had alleged that Shermeta "aided and abetted" Gilbertson in the manipulation of Dakota Plains' stock price during its first 20 days of trading. The stock popped to $12, triggering a nearly $30 million bonus to Dakota Plains' noteholders, which included Gilbertson. Gilbertson has denied the charges against him.

In November 2016, Shermeta consented to a U.S. Securities and Exchange Commission order in connection with Dakota Plains. The SEC found he solicited investors for Dakota Plains, but improperly brokered sales through an unregistered securities firm. Shermeta agreed to pay $136,000 without admitting or denying the SEC's findings.

Dakota Plains, which was involved in North Dakota's oil industry, filed for bankruptcy in 2016. Its assets were later sold.