MANCHESTER — The unexplained death of veteran wrestling coach Jason Cumming was preceded by a highly critical, anonymous letter about his coaching style and behavior around the teenage girls he coached, the New Hampshire Union Leader has confirmed.

The letter was emailed to the Union Leader, other media, Manchester school officials, wrestling coaches and other New Hampshire high school sports officials.

Last week, police acknowledged the letter is the basis for an investigation into Cumming.

But friends of Cumming dispute the letter and said it takes actions of Cumming — the longtime coach of the Central High School wrestling team and founder of the wrestling program at the Manchester Police Athletic League — out of context.

“(The letter took) every little thing someone would look at and make it a negative thing; that’s what someone was trying to do,” said Rob Waters, a coach of the Keene Gladiators wrestling club.

Waters said his wife drove his two daughters to Manchester once a week to be coached by Cumming, and said his older daughter is ranked 18th in the country for her wrestling abilities.

“He treated every (student wrestler) like his own child,” Waters said. He would trust Cumming with his daughters without question, he said.

Cumming was found dead at his Reed Street home on the afternoon of April 11. Police have called the death an unattended death, the term used when someone dies alone.

Kim Fallon, the chief forensic investigator for New Hampshire, said the cause of death won’t be determined for several weeks. The death is not considered suspicious, she said.

The author of the six-page letter wrote that several other parents, coaches and supporters suspect Cumming was grooming female wrestlers and other student-athletes for possible sexual encounters. The letter recounts several instances of possible boundary violations. It accuses him of violating rules governing club and high school wrestling. And it questions his actions as a role model.

The mother of a Massachusetts wrestler told the Union Leader she complained to the Manchester Police Athletic League about Cumming in March, after he pressured her to chaperone an upcoming tournament in New York. At that point, league officials told her that Cumming identified her as a chaperone during a trip to Cornell, N.Y., last November.

Although the mom attended the tournament with her daughter, she said she did not chaperone for Cumming, who was there alone with two girls from the league, she said. She believes that discovery prompted the league to force Cumming to resign.

“I do know his actions crossed the line as far as being a high school coach and volunteer coach,” said the mother. She asked that her name not be used for fear that she and her daughter would be shunned in the wrestling community.

Manchester police launched an investigation based on the letter, according to police spokesman Capt. Brian O’Keefe. O’Keefe said the letter was emailed on the night of April 10.

O’Keefe stressed that the allegations do not appear to be criminal.

“A full investigation will be completed to ensure no criminal laws were broken,” he wrote in an email.

The Manchester Police Athletic League is closely aligned with Manchester police. Some officers provide coaching and sit on the league’s board. The board vice chairman is former Police Chief David Mara.

“This will be treated no differently than any other investigation regardless of who is involved, therefore our detectives will handle the investigation, which is active and ongoing,” O’Keefe said.

Cumming also coached girls’ soccer at St. Joseph Regional High School, The Derryfield School and Central High in the past, according to his obituary. Manchester schools have consistently refused to answer any questions about Cumming, other than that he was a coach of the Central team.

The Air Force veteran was also employed for a time as a resident counselor at Crotched Mountain Rehabilitation Center, according to the obituary.

The letter contrasts with more than 150 comments on the league’s Facebook page that offer praise for Cumming and anguish over his loss.

“I’ve never seen a more welcoming coach,” said Matt Nhoury of Haverhill, whose daughter was invited to wrestle with a Cumming team. “Always interested in how things were going with her in and off the mat. Just a tremendous person with a great spirit.”

Anna M. Tomeu Lopez recounted how Cumming supported her 7-year-old grandson during a wrestling tournament in Salem. Cumming was by his side the whole time.

“Have no idea how I am going to tell him,” she wrote.

“One of the most amazing coaches I’ve ever had. We will miss him more than anything,” wrote Shandria Waters.

Waters said the New Hampshire wrestling community is close. Many students are on high school teams, and the more dedicated ones are in clubs, such as the Manchester Police Athletic League’s Gryphons that Cumming helped start. Cumming invited dedicated wrestlers to visit the league for a practice, and he gave tips to fellow coaches.

“Jason was very black and white with everyone,” Waters said. “He was very blunt, but he was never degrading at all.”

Waters said he had spoken to Cumming on Wednesday afternoon. Cumming had unexpectedly resigned from the police league, but appeared in good spirits. The problems would blow over, and he still had his Central job, he told Waters.

“Then the letter hit. I think it was one of those things: too much, too fast,” Waters said.