It’s a three-decade-old, high-profile murder case that has received national attention.

The person in the below composite sketch is the man investigators believe is the I-70 Serial Killer.

The sketches below are age-enhanced. These show what the killer could look like now.

What happened?

According to police, six store clerks along Interstate 70 were killed in a murder spree over 29 days. Two in Indiana, two in Kansas and two in Illinois.

Detectives said the scenario for all six murders was basically the same. The killer walked in, shot the clerk in the back of the head and then left all in broad daylight, all with the same gun.

Terre Haute Police Detective Sergeant Troy Davis has been working on this case for more than ten years. The three-state killing spree claimed six lives – one in Terre Haute.

“I certainly wouldn’t call it a cold case now,” Davis said. “Even after 30 years, you might think people would get over it, but they don’t, they don’t get over it.”

Michael “Mick” McCown – Terre Haute’s victim

On April 27, 1992, the I-70 killer claimed the life of 40-year-old Michael “Mick” McCown. He was working as a store clerk at his family’s ceramics store.

This was on south 3rd Street in Terre Haute.

According to police, McCown was the I-70 Killer’s only male victim.

Davis stays connected with McCown’s family.

“When I see them (McCown’s family), especially when they get emotional…they still get emotional after 30 years, and that’s something that affects you,” Davis said.

Heating back up

Terre Haute Police Detective Brad Rumsey says he believes his department has an edge in solving this case.

“There’s no reason not to be focused on him, but you don’t want to put all of your eggs in one basket. There’s always the possibility that this sketch could be off,” Rumsey said. “Maybe it’s one of those deals where someone was in the wrong place at the wrong time. You have to count on other things, not just the picture.”

The other things include the fact that the killer used a unique gun to shoot his victims. Ballistics link the deaths.

All of the agencies involved in this investigation have sent items away for DNA testing. Investigators hope DNA matches up and there’s a connection.

Davis says he’s witnessed firsthand this cold case warming back up in the last two years. Heat brought on by all the law enforcement agencies investigating the case.

Davis says, yes, they have a facial composite of the suspect, and ballistics link the deaths, but they need more. That’s where advancements in technology come in.

All agencies working on this mystery have evidence that’s been sent away for DNA testing. The results from the testing could lead to the killer’s identity.

Davis says the hard part is waiting – but he believes Terre Haute could solve the case.

All of the agencies involved in this investigation have sent items away for DNA testing. Investigators hope DNA matches up and there’s a connection.

Rumsey says the THPD has never given up. He says the families deserve closure.

“When you let a case go cold because of the evidence…or lack thereof…you get antsy. You want to move forward,” Rumsey said. “For me, it just means we are still behind the eight-ball. We need to get there.”

He told us tips from the public continue to move this case forward. An information portal was created for all of the agencies involved.

Davis told News 10 that around eight to ten tips are received each week.

You can share information by calling 1-800-800-3510 or by clicking here.

Police are offering a $25,000 reward.