Wide receiver Tyreek Hill is the subject of an NFL investigation.
CNN  — 

In a letter to the NFL, Kansas City Chiefs receiver Tyreek Hill denies he has ever punched his son or grabbed the boy’s arms, and his lawyer says he has text messages that show Hill’s fiancée has hurt the child in the past, ESPN reported Thursday.

The three-plus-page letter, signed by one of Hill’s attorneys and obtained by ESPN, says the two-time All-Pro will cooperate with the league’s investigation into allegations Hill abused his 3-year-old son.

After audio was made public last week purportedly of Hill’s fiancée, Crystal Espinal, suggesting the Chiefs player broke their son’s arm, the team announced he will not participate in team activities indefinitely.

CNN has not authenticated the audio, which was obtained and published last week by CNN affiliate KCTV. Its release follows the announcement by a Kansas prosecutor that Hill and Espinal will not be criminally charged in connection with an investigation into their child’s welfare.

CNN has reached out to Hill’s attorney and Espinal for a comment.

In a letter to Lisa M. Friel, the NFL’s special counsel for investigations, attorney N. Trey Pettlon writes that Hill denies he has ever punched his son, grabbed his arms, or otherwise touched the boy mean-spiritedly to discipline him.

Hill does sometimes tap his son on the chest and tell him to man up or not to cry, the letter says, and the father and son also play fight.

Pettlon writes that Espinal punishes the child and that there are text messages about her spanking the boy so hard it left marks. The attorney did not provide screen shots of the purported texts, nor does he give a date when the exchange took place.

Tyreek: ‘Crystal you know I didn’t cause any bruising or harm to (our son.) But for some reason I still may be charged.’

Crystal: ‘I know you didn’t. I did. I hurt (our son), I’m the one that did it. I was hurt and mad at you so I blamed you for everything.’

In the audio made public last week, Hill and Espinal appear to discuss the police investigation of alleged abuse of their son, whose name is bleeped out.

Espinal asks, “Why does (the unnamed child) say, ‘Daddy did it?’”

Later in the recording, she states, “A 3-year-old is not going to lie about what happened to his arm.”

Hill denies breaking his son’s arm in the recording. He also says, according to the recording, “I’m the one that gets physical with him,” referring to the child.

“He is terrified of you,” Espinal says of their son, according to the audio.

Hill responds, “You need to be terrified of me, too, b—-.”

Pettlon says that comment was inexcusable, and Hill didn’t ask him to defend it.

He also notes the criminal investigation has concluded with no charges.

Johnson County, Kansas, District Attorney Steve Howe said last week that his office would not press criminal charges in the case.

“We are deeply troubled by this situation and are concerned about the health and welfare of the child in question,” Howe told reporter. “We believe that a crime has occurred. However, the evidence in this case does not conclusively establish who committed the crime against this child.

“Despite this decision, there will be continued involvement by State officials to ensure the safety of the child,” the prosecutor said.

Howe declined to discuss who has custody of the child, but added, “What I can say is that the child is safe.”

Copies of Hill’s letter were sent to the players’ union, the Chiefs and agent Drew Rosenhaus.

CNN’s Sheena Jones contributed to this report.