Individuals released from prisons in the state of Washington were 12 times more likely to die of drug overdoses and 10 times more likely to be murdered than other Americans, according to researchers from the University of Colorado.

The Age reported Jan. 11 that researchers tracked more than 30,000 prisoners for two years after their release between 1999 and 2003. They found that the first few weeks after release were the most dangerous. "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 lead researcher Ingrid Binswanger. "But you might not expect the higher death rate to be as dramatic as it is."

Overall, released inmates were four times more likely to die of any cause in the year after release. Researchers speculated that the high number of overdoses may be due to heroin and cocaine users overestimating their dosages after a period of enforced abstinence.

The study was published in the Jan. 11, 2007 issue of the New England Journal of Medicine.