In August 1975, FBI investigators confirmed that at least eight (possible as many as forty) men had been murdered in the Veteran's Hospital in Ann Arbor, Michigan. The cause of the deaths was believed to be the injection of a drug called Pavulon which resulted in respiratory arrest in the victims.

Nurses Leonora Perez and Filipina Narcosa were arrested and charged with murder in June of 1976. The two were the only nurses regularly on duty at the times of the suspicious deaths, though they were never actually seen injecting the patients with any drugs. At trial witnesses did, however, recall seeing one of both in the victims rooms prior to or during the time of death. The circumstantial evidence did not hold up and murder charges were withdrawn against Perez before the end of the trial and Narcosa was found not guilty of the murders, though both were found guilty of poisoning and conspiracy to committ murder.

The verdict was appealed and a new trial ordered in 1978. The prosection still could not come up with more concrete evidence and all charges against Perez and Narcosa were dismissed.