30 Years After the 'I-70 Killer' Began His Murder Spree, Detectives Still Don't Know His Name

Thirty years after six people were fatally shot in a string of killings along the I-70 corridor, the person responsible for the murders remains a mystery.

"To this day, we can't figure out why someone would go on this shooting rampage and just kill people for no apparent reason," Det. Kelly Rhodes with the St. Charles Police Department in Missouri tells PEOPLE. "I can only describe it as evil."

The spring of 1992 is when all hell broke loose for six families and their respective police departments. The "I-70 Killer," as he's been coined, is a man authorities believe went on a shooting spree that spanned across three Midwest states in a matter of 29 days.

Robin Fuldauer of Indianapolis, Ind.; Patricia Mager and Patricia Smith of Wichita, Kan.; Michael McCown of Terre Haute, Ind.; Nancy Kitzmiller of St. Charles, Mo.; and Sarah Blessing of Raytown, Mo., were all shot to death.

Apart from one male victim whom police believe was mistaken for a woman, the remaining five victims were female — and their murders shared similarities too striking to miss. The victims were all white store clerks working in small businesses along I-70. Each was in their mid-20s to mid-30s with long brown hair. And all were killed "execution style" — shot in the back of the head — with the same gun: an Erma Werke Model ET22 pistol.

Police in Kansas, Indiana and Missouri quickly realized they had a serial killer on their hands.

But, the case quickly went cold. Although detectives were able to put together a facial composite of the suspect and link the homicides through ballistics, the investigation kept hitting a wall.

Three decades and hundreds of leads later, Rhodes' sole task in the SCPD is to now hunt down the murderer that's evaded police for so long.

Her days are spent rereading original police reports, re-examining evidence and pursuing new leads. Police hope her fresh take on the case, paired with advancements in technology, will push the investigation to the finish line.

"This is a case that St. Charles city has never given up on," she says.

Since 1992, detectives believe the killer may have struck three more times: twice in Texas in 1993, and again in Kansas in 2001.

Rhodes revealed that in November 2021, efforts were increased across all agencies involved. A uniform task force was launched and investigators from Kansas, Indiana and Missouri came together to discuss each case, review the evidence and develop a plan to move forward.

"We really have to work all together to do this, and with all the agencies working together and sending everything off to the lab, everything combined that we have, I feel very hopeful for this case. I really do," Rhodes shares.

"This is the future, so we're really hoping we get some good DNA from evidence. It's not like we're sending off one piece and hoping on that one piece, we have quite a bit that we've sent off," she says, although she could not disclose the specific types of evidence being tested.

Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

While taking a serial killer off the streets would grant Rhodes much satisfaction, bringing long-awaited closure and justice to the six families only adds to her desire to solve the decades-old cold case.

"I've been asked by a lot of people: 'Why now? This case is 30 years old, why focus on this case when there's murders happening, right now?'" she says. "And, I always tell them, 'Whether someone was killed three minutes ago or three decades ago, it doesn't matter. Every single one of these people — their lives mattered.'"

"We're not going to stop until we feel every stone has been unturned." She adds, "We've already been fighting for this and the families have been fighting for 30 years, so we're definitely not about to give up now."

Anyone with information about the slayings is asked to contact the St. Charles Police Department at 1-800-800-3510. Police are offering a $25,000 reward.