Story highlights Athletes voice support, with LeBron James saying the death "makes no sense at all"

The boyfriend of the toddler's mother is accused of assaulting the child

St. Paul Pioneer Press: Grandfather says the child is Adrian Peterson's son

Adrian Peterson tweets his thanks for the support he's received

A 2-year-old boy who was reportedly the son of Minnesota Vikings star Adrian Peterson died Friday of injuries he suffered after allegedly being abused, police said.

Sioux Falls, South Dakota, police said Joseph Robert Patterson, 27, has been charged with aggravated battery of an infant and aggravated assault. If convicted on the charges, both felonies, Patterson could face up to 40 years in prison and an $80,000 fine.

Prosecutors are considering filing additional charges against Patterson in light of the boy's death, according to police.

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.

"God Bless everyone and thank u so much," he wrote

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

Even if he wasn't talking, many athletes were. The Washington Redskins' Robert Griffin III and Houston Texans' defense lineman J.J. Watt were among Peterson's competitors who expressed condolences online, as well as their shock at what happened.

Among the most vocal was LeBron James, who has won the NBA's MVP award four of the past five seasons. Declaring "ol buddy will get what's coming to him!!" -- an apparent reference to the suspect -- James expressed the sorrow he felt, as a young father himself, while offering support to his friend.