CNN  — 

It’s no secret that American’s jails and prisons are among the most dangerous and overcrowded in the world. But news of former NFLer Aaron Hernandez’s suicide in prison highlighted a recent overlooked trend in corrections facilities nationwide.

According to the U.S. Department of Justice’s Bureau of Justice Statistics:

Suicide rates in prisons are rising

  • After holding steady for years, suicide rates started rising sharply in 2013.
  • In state prisons, it went up 30% from 2013 to 2014.
  • In 2014, there were 3,927 inmate deaths in state (3,483) and federal (444) prisons, the largest number of inmate deaths reported since tracking began in 2001. Although illness remained the most common cause of death, suicides represented 7%. That’s the largest percentage of deaths due to suicide since tracking began.

How prisons keep their suicidal inmates on watch

Massachusetts has the fourth-highest rate

  • Between 2001 and 2014, Massachusetts, where Hernandez was in custody, had 32 suicides per 100,000 state and federal prisoners.
  • That’s almost twice the national average and the fourth highest in the country.

CNN’s David Heath contributed to this report.