ST. CHARLES, Mo. (KMOV.com) -- Inside the St. Charles Police Department, there is a room full of thousands of files related to the man known as the I-70/35 serial killer.
St. Charles Police Detective Donald Stepp says there are 10 drawers that contain thousands of names, all possible connections to a 1992 crime spree that left six people dead across three states.
The I-70/35 killer got his name because because several of his victims worked in stores just off of Interstate 70.
One of those victims was 24-year-old Nancy Kitzmiller, who was killed in a store in St. Charles.
On Sunday, May 3rd 1992, Kitzmiller was working alone at The Boot Village just off Interstate 70 at Zumbehl Road.
According to Stepp, Kitzmiller wasn't supposed to work that day. She was filling in for another employee.
At approximately 2:30 that afternoon, she was discovered shot to death in the back of the store.
There was no surveillance video, no witnesses and no known motive.
Years later, cold case investigators would simply guess the killer's motive "has always simply seemed to be the thrill of killing.”
But Kitzmiller was not the I-70 killer’s first victim. In fact, she was next to last.
The Killing Spree
The three state, 29-day killing streak started in Indiana.
On April 8th 1992, Robin Fuldauer was shot to death inside a Payless Shoe Store in Indianapolis.
Three days later on April 11th, 1992, two woman were found shot to death inside a Bridal Store in Wichita, Kansas.
Victims Patricia Smith and Patricia Magers stayed late to wait for a customer needing a cummerbund.
Neither made it home.
Detective Tim Relph of the Wichita police department worked the case 28 years ago, and it's there where authorities caught a break: an eyewitness account.
Relph said the customer the women were waiting late for arrived at the store and saw the man.
From that encounter, a composite sketch was created.
But investigators believe the key to solving the case lies with the suspected murder weapon.
The police believe the killer used an Erma Werke Model ET22 pistol, a distinct gun with a nearly foot-long barrel.
“It's actually a historical remake of an old German navy pistol," said Relph. "The barrel is long enough where the gun has a wooden forearm."
Just two weeks after the double murder in Wichita, the killer struck again.
April 27th at Sylvia's Ceramics in Terra Haute, Indiana the killer claimed his only male victim, Michael McCown. Police believe the killer mistook McCown for a woman because McCown had long hair, and the killer saw him from behind.
A week later, Nancy Kitzmiller was killed in St Charles.
Four days after that on May 7th, 1992, Sarah Blessing was shot to the death inside a small store in Raytown, just outside Kansas City.
The trail goes cold
As the 90s faded into the new century, the story fell out of the headlines. But for the families impacted it will never be forgotten.
Nancy Kitzmiller’s parents have done interviews over the years, hoping to keep the case in the public eye.
In 2016, Carol Kitzmiller told News 4 “every single day, you think about her.”
Her husband, Don, hopes continuing coverage of the story will lead to someone coming forward with a clue.
“There's no reason not to say anything," he said in 2016. "It benefits society, benefit us."
And despite decades of frustration, Stepp has not given up hope.
“We're not going to give up on this case. We have individuals working on this case in several states and cities," he said. "We believe this case is solvable."
The FBI has examined the evidence, and their profilers believe, given the geography and the timing, they know where the killer lived in 1992.
“This case has been looked at two separate times by FBI profilers. Both times they believed the killer is from the Indianapolis area” said Stepp, “There’s nothing out there saying he is not alive. I believe he's still alive and out there.”