A judge on Thursday found an Eden Prairie man who drowned his baby son in a laundry tub not guilty by reason of mental illness.

As 13 family members looked on, Randel Richardson calmly admitted holding 7-month-old Rowan under the water July 31 while his wife shopped for groceries. His wife, Kari, looked on and cried quietly as the judge read the facts of the case.

Hennepin County District Judge Mark Wernick cited reports from three psychologists for the court, prosecutors and defense who agreed that Richardson, 37, had a mental illness that prohibited him from understanding the consequences of his actions when he killed his son.

Wernick said Richardson "was laboring under such defective reasoning" that the not-guilty verdict is supported. Richardson, who had been on medical leave from his job of 13 years at Cargill because of mental health problems, drowned his son "to spare him from the suffering that was going to occur" because he believed he could not provide for his family, court documents said.

He later told a psychologist he had no feelings at the time and seemed to be watching himself as he held the baby under the water.

According to charges, after the drowning, Richardson went upstairs and waited for his wife. When police arrived, he told them, "I did this on purpose," the criminal complaint said.

In light of Thursday's verdict, the county attorney is expected to file a petition for civil commitment, asking that Richardson be declared mentally ill and dangerous, and detained for treatment.

Meanwhile, he is expected to be taken to the Minnesota Security Hospital in St. Peter for a 60-day evaluation. After that, Wernick likely will determine whether he should be committed and where. Theoretically, Richardson could one day be released, said his attorney, Tony Edwards.

"I hope that day will come," Edwards said. "How soon that comes and what form it takes depends on things that are entirely out of my control in terms of emotional and mental issues. I think it is likely that one day it will happen, but it may not happen for some time."

County Attorney Mike Freeman declined to comment on the case pending the commitment hearing.

Edwards called the type of verdict rendered Thursday "extraordinarily rare."

"Mentally ill people go to prison all the time," he said. "Being mentally ill is not an excuse or a justification for committing a crime. What's different here is being mentally ill in such a way as to not understand the nature or the wrongfulness of what your actions are."

However, the insanity defense has proved successful in recent years in a few high-profile cases. In February 2010, a Dakota County judge found Stephen R. Miles not guilty for that reason in connection with the decapitation of his stepmother in her Burnsville home in 2005.

In Ramsey County earlier this month, Timothy E. Novak was found not guilty by reason of insanity in connection with the August 2010 stabbing death of his grandfather. Both men were sent to St. Peter.

Family, friends stand by him

Since the drowning, Kari Richardson and a legion of family members have stood by Randel Richardson, attended his hearings and visited him in jail, where he's remained since Rowan's death. Family members declined to comment after the hearing. The couple's other two children, ages 12 and 9, were not at the hearing.

Richardson, who earned $90,000 a year as a supply-chain analyst at Cargill, had no criminal history. He'd struggled with depression and mental illness leading up to Rowan's death but was being treated with medication.

Edwards said Richardson is "a completely different person" from the "essentially catatonic" man he was nine months ago.

"He absolutely understands what happened; he's devastated by it, and now he has to deal with the repercussions of that, as does his family. It's very difficult." Edwards said.

"He really has led a life as a solid father, husband and neighbor, and that's fundamentally the person he is, despite what happened."

Abby Simons • 612-673-4921