Records from Washington state show that 30,237 prisoners released from 1999 to 2003 were 12 times as likely to die from a drug overdose and 10 times as likely to be slain in a two-year period than the general population.
The study, also in today's New England Journal of Medicine, said the reasons go beyond the bad habits and willingness to take risks that probably landed people in prison in the first place.
"We know this is a population that has a higher rate of smoking, higher rate of mental health problems, higher rate of chemical dependency and more risk-taking behavior," said Ingrid A. Binswanger of the University of Colorado.
During the two-week period immediately after release, compared with years later, ex-prisoners were 29 times as likely to die from cocaine, 34 times as likely to die from a heroin overdose, 15 times as likely to be killed by alcohol, more than twice as likely to be gunned down and nearly eight times as likely to commit suicide.