NFL star Adrian Peterson's 2-year-old son dies after assault

SIOUX FALLS, S.D. (CNN) -- Minnesota Vikings star Adrian Peterson’s 2-year-old son died Friday after allegedly being beaten by the mother’s boyfriend, police said.

Before the boy died of his injuries, Sioux Falls, S.D., police said Joseph Robert Patterson, 27, had been charged with aggravated battery of an infant and aggravated assault. He’s likely to be charged with murder now.

Soon after the news came out of the boy's death, Adrian Peterson took to Twitter to express his gratitude to his family, fans and the "fraternity of brothers" in the NFL for their support.

"Thank you to my family, my fans and fans of other teams for their support," he wrote.

Seahawks coach Pete Carroll issued a statement: ”Can't express how much sadness we are feeling for Adrian Peterson. Our deepest condolences go out to him as he deals with this tragic loss.”

Patterson called authorities about 5:45 p.m. Wednesday to a report that a 2-year-old was choking in his Sioux Falls apartment, police spokesman Sam Clemens said. Officers arrived to find that the toddler was unresponsive, and he was rushed to a nearby hospital.

Authorities determined that the child had suffered injuries to his head consistent with abuse, according to Clemens. Police said Patterson, whom they described as the boyfriend of the injured child's mother, was the only other person in the residence at the time.

The suspect -- who was given suspended sentences a year ago for simple domestic assault and violation of a domestic abuse bond, both misdemeanors -- was arrested Thursday night, said Lincoln County, South Dakota, State's Attorney Tom Wollman. A judge set his bail at $750,000 cash during his initial court appearance Friday, according to Clemens.

The 2-year-old's mother is not under investigation, Clemens added.

"This is an absolute tragedy," Wollman said Friday, "and the parents and the extended family are suffering greatly."

Authorities have declined to name the child, with police saying that information is "being withheld out of respect for the family and to give them time to make notification."

Peterson's father, Nelson Peterson, told the St. Paul Pioneer Press that the injured toddler is his grandson and Adrian's son. Nelson Peterson did not identify the boy by name except to say he is not Adrian Peterson Jr.

The 2012 NFL Most Valuable Player himself did not elaborate on what happened when addressing reporters earlier Friday, at which time the child was in critical condition. But he did acknowledge that he was dealing with "a private matter," adding that he still plans to play in Sunday's game against the Carolina Panthers.

"I will ask you all to please just respect my privacy," Peterson said.