On November 27, 1973, 11-year-old Penny Schroeder vanished from her school in Clinton, Maryland. As the daughter of a police lieutenant, her disappearance prompted a swift law enforcement response, and her body was found hours later, in some woods five blocks from school. 

The child had been molested, strangled, stabbed repeatedly, her skull fractured by crushing blows in a grisly example of overkill.

Penny's murder came nine weeks after the slaying of 21-year-old Susan Fallin, whose charred body was recovered from a burned-out car near Brandywine, October 5. Police had no evidence to link the crimes, but this time there were witnesses who told of seeing Penny with a teenage boy before she disappeared. 

Descriptions led authorities to janitor Edward Holmes, 19, and he was taken into custody November 28, charged the same day with the murders of two children in Washington, D.C. The capital victims were listed as nine-year-old Stanford Kendrick, abducted from school on September 20, and 12-year-old Joanie Bradley, kidnapped in similar fashion October 16.

Like Penny Schroeder, both of the earlier victims had been molested, their bodies discarded in woods near their respective schools. Again, like Penny, Joanie Bradley was a campus monitor, apparently snatched while "on duty," patrolling the playground.

In custody, Holmes freely confessed to the three murders charged against him.

Michael Newton - An Encyclopedia of Modern Serial Killers