The verdict late Tuesday came after a three-week trial in which Joseph Patterson called on "an international team of expert witnesses," said Lincoln County, South Dakota, State's Attorney Thomas Wollmann. The defense claimed the child choked, spurring biological reactions that (along with the CPR performed) could have explained the abuse allegations -- including bruises and other injuries.
"That flies in the face of all the literature," Wollmann told CNN. "... Our good old, down home, common sense-filled jurors just didn't buy it."
Instead, the jury convicted the 29-year-old Patterson for first-degree manslaughter, aggravated battery of an infant as well as second-degree murder.
The conviction dates back to an incident in October 2013 and involved Peterson's then 2-year-old son, Tyrese Ruffin, who was not living with the Minnesota Vikings running back but rather with his mother in Sioux Falls, South Dakota.
Patterson, who was the mother's girlfriend, lived there with them.
Authorities found the child unresponsive and later determined he'd suffered injuries to his head consistent with abuse. Patterson, however, claimed that the boy died accidentally after choking on food.
Peterson acknowledged the late child was his son, then played in a game a few days later
"God wants good to come from it," he texted Fox sideline reporter Laura Okmin
before the game, Peterson said. "We mourn and grieve, but heaven had the baddest welcoming party for my son. That knowledge gives me peace.
"I'm still hurt and feel the pain of life," he added, according to Fox. "But I'm able to function because of the peace and joy of knowing my loved ones are in a much better place."
The 2012 NFL most valuable player himself ran into trouble a year later for his own actions against another of his children -- another son, who was 4 at the time.
Initially charged with felony child abuse, Peterson pleaded no contest to misdemeanor reckless assault in November 2014 in Texas. The NFL then suspended him without pay and he lost his appeal of that sanction the next month.
In February, a Minnesota district court judge vacated the decision that upheld his suspension, making Peterson eligible for reinstatement.
And he's come back strong, rushing for 291 yards in the first three games of this season.