The other nurses had noticed a high number of deaths on Gilbert’s time, but unfortunately they passed it off, jokingly calling her the “Angel of Death“. Until finally in 1996, three nurses reported an increase in cardiac arrest deaths and a decrease in the supply of epinephrine, this was enough information to trigger an investigation.The prosecutor in her case, Assistant U.S. Attorney William M. Welch II, asserted that Gilbert was having an affair with a security guard at the hospital. The security guard, James Perrault, testified against her, to the point of saying that she’d confessed at least one killing to him. The defense attorney, David P. Hoose, claimed reasonable doubt, based on a lack of direct evidence.

Kristen was a single mother of two, was convicted on March 14, 2001 in federal court. Though Massachusetts does not have capital punishment, her crimes were committed on federal soil and thus subject to the death penalty; however, upon the jury’s recommendation, she was sentenced to life in prison.