The number of US prisoners who are murdered in jail or commit suicide has dropped dramatically since 1980, according to the government.
Many suicides occurred within the first week in custody
Murder in state prisons fell by more than 90% from 1980 to 2002, and suicide rates dropped by 60%.
Civil rights groups say the falling figures are due to a better separation of violent and non-violent inmates.
The report, compiled by the US justice department, compares death in custody in 1980 with 2002.
Murders in state prisons fell from 54 per 100,000 prisoners in 1980 to four per 100,000 in 2002, the department said.
It also found that, between 2001 and 2002, almost 43% of all prison murders happened in three states - California, Texas and Maryland.
Civil rights groups say the figures reflect improvements in mental health care and medical treatment in prisons which currently have about 2.1 million people.
"There's much more awareness about the problem of suicides in jails," Lindsay Hayes of the National Centre on Institutions and Alternatives, told the Associated Press news agency.
"Twenty years ago, if you asked a sheriff, he wouldn't have information on it or any sensitivity to it. It wouldn't be on his radar screen."
Suicides - the leading cause of death in custody in 1983 - fell from 34 per 100,000 to 14 per 100,000 in 2002.
Between 2000 to 2003, white inmates were more than six times more likely to commit suicide that black inmates and almost half of all suicides occurred within the first week in custody.