Jim Carlson, a head shop owner found guilty in 2013 on dozens of felony charges after experts said he sold enough synthetic drugs to cause a public health crisis in Duluth, had his sentence commuted Thursday as one of nearly 1,500 convicted criminals granted clemency by President Joe Biden.

Carlson received a 17½-year sentence after a jury found him guilty on 51 of 55 felony counts for selling synthetic drugs from his store in downtown Duluth. His two-week federal trial in Minneapolis, considered the most significant trial in Minnesota involving synthetic drugs, included charges of conspiracy, misbranding drugs, distributing a controlled substance and making illegal monetary transactions.

His girlfriend, Lava Marie Haugen, was also convicted on four felony counts, and his son, Joseph Gellerman, was acquitted on two felony counts but convicted of two misdemeanors.

In addition to the commutations announced Thursday, Biden pardoned 39 people, including three Minnesotans. Those with commuted sentences had been placed in home confinement during the COVID-19 pandemic, and those pardoned were convicted of nonviolent crimes that included drug offenses. The White House called Biden's act "the largest single-day grant of clemency in modern history."

According to the news blog Perfect Duluth Day, Carlson will be officially released Dec. 22 but serve probation for the next few years. After serving time at a low-security federal prison in Michigan, he has been monitored by authorities at an undisclosed location.

Long lines of addicts were drawn to his store, called the Last Place on Earth, to the consternation of other downtown businesses. A business owner next door said Carlson's store had made it "like a crack neighborhood."

Prosecutors alleged Carlson sold synthetic drugs that were misbranded as incense, potpourri, bath salts and glass cleaner, while using employees as guinea pigs to test how the unregulated drugs worked on customers.

At his sentencing in August 2014, he argued at length that the government had led him to believe the drugs he sold were legal and that the nation's war on drugs was a failure. "Is this your 'Reefer Madness' moment?" he asked U.S. District Judge David Doty, referring to the movie made to scare people from smoking marijuana.

Carlson, Haugen and Gellerman appealed their convictions. Defense attorneys argued that he didn't think he was committing a crime because the synthetic drugs he sold differed from prohibited chemicals. But they lost their appeals, with the court finding that he knew the chemical structures of the products he sold were substantially similar to controlled substances.