The Route 40 Killer — and the Rookie Female Cop Who Caught Him

By bravely going into danger undercover, she was instrumental in bringing Steven Brian Pennell down.

Verity Partington
9 min readMay 14, 2021


Serial killer Steven Brian Pennell
Steven Pennell (Image: Only in Your State)

It was one of most shocking serial murder cases the US had ever seen — and it was the first to have taken place in Delaware. As women disappeared off the streets in 1987 and 1988, police and the FBI joined forces to catch the man who had been dubbed the Route 40 (or I-40) Killer.

But it was only when they took an incredible risk — and a young female police officer stepped up to go far beyond the line of duty — that the perpetrator was finally brought to justice.

First victim — and a sadistic murder

Shirley Ellis was 23 when she left Wilmington Hospital on November 29th 1987. She had been studying to be a nurse and was visiting a friend sick with AIDS to take him a home-cooked meal for Thanksgiving.

Although Shirley had had a turbulent few years in which she had resorted to sex work to make ends meet, her family said she had recently decided to turn her life around and retrain to give her more purpose.

She planned to hitchhike home along Route 40 that night, but she never made it home. Shirley was later found by the roadside with horrific injuries. She had been strangled with a ligature, beaten around the head with a hammer, and — most chilling of all — had her breasts mutilated.

There was duct tape in her hair, but that was about all police had to go on. After seven months of chasing down false lead after false lead, Shirley’s had become a cold case.

Dealing with a serial offender

Then, on June 29th 1988, another body was discovered. Catherine DiMauro was 31 years old and also had a history as a sex worker. She had been seen walking along Route 40 at 11:30 PM the previous night, but had subsequently vanished.

Like Shirley, Catherine was found with mutilation to her breasts and multiple blunt force injuries. She had been strangled to death and also had duct tape in her hair. This time, police found blue and red fibres clinging to her body too.



Verity Partington

A writer and author of crime thrillers living in the UK. Partial to books, stationery, papercrafts and walking. You can find her books on Amazon here: https://a