DENVER -- An Arapahoe county sheriff's report suggests Broncos wide receiver Kenny McKinley, who is thought to have killed himself with a gunshot to the head, had been depressed over a knee surgery.

"He had made statements while playing dominoes shortly after the surgery that he should just kill himself," the officer reported. "No one believed he was serious."

McKinley's teammates and coaches said Tuesday that they didn't see any hint the gregarious 23-year-old wide receiver was suicidal

Last year, 940 Coloradans died by suicide, according to the Colorado Department of Public Health and Environment.

That is 18.4 deaths per 100,000 residents

The largest increase was in men 25 to 44 years old.

"It is important to note that some people who die by suicide do not show any suicide warning signs. However, about 75 percent of those who die by suicide do exhibit some warning signs and these should always be taken seriously, said Dr. Dianne McCallister, chief medical officer at Porter Adventist Hospital.

A few warning signs can include:

Appearing sad or depressed most of the time
Loss of interest in most activities
Talking or writing about death or suicide
Withdrawing from family and friends
Dramatic mood changes
Strong anger or rage
Exhibiting a change in personality
Giving away prized possessions
Acting impulsively or recklessly

"Oftentimes family and friends do not take warning signs seriously. If someone is talking about ending their life, an evaluation by a licensed clinical professional is essential. The sooner the better," said McCallister.

Emergency rooms in the Denver area can assess and determine the most appropriate level of care for suicidal thoughts, feelings and plans.

Helpful resources on suicide prevention:

www.namicolorado.org
www.cdc.gov

Dr. McCallister is on 7NEWS at 11 a.m. every Wednesday. If you have a topic or question you would like her to discuss, email 11am@thedenverchannel.com.