MADISON - A killer on the loose: a Madison man was stabbed to death in his home.

Now, four months later, his parents want to know why police haven't caught the killer.

Madison police are working to solve three high profile murder cases right now. The families of Kelly Nolan, Joel Marino and Brittany Zimmermann want justice.

The Marino family met with the state attorney general's office Thursday. They say they want state investigators to take over their son's homicide case because they don't feel that the Madison police can solve it.

Louis and Debbie Marino have been mourning the loss of their son Joel for months.

The 31-year-old medical educator was stabbed to death inside his Madison home on January 28.

The Marinos originally thought the Madison Police Department could handle their son's murder case, but they don't think that anymore.

"My son's case, no, they haven't been doing the job as far as I'm concerned. I've had a number of experiences and have been very disappointed in what's been going on," Louis Marino said.

"We can't allow the lack of further investigation to continue any further," Louis Marino said.

There are five unsolved homicide cases in Madison in the past year. Kelly Nolan was murdered last summer. Brittany Zimmermann was killed inside her home in April.

The Marinos believe her killer may be the same man who killed their son.

"The similarities are very close," Debbie Marino said.

Madison police say they have strong investigators on the Marino case.

Madison Police spokesperson Joel DeSpain says, "We feel for that family and are working hard to bring justice to the case."

"It's been over 90 days, and unless we get help from outside, the Madison Police Department, I don't think this case will ever be solved," Louis Marino said.

The attorney generals office told the Marinos that they are not allowed to take over the case unless the Madison Police Department asks them to. The Madison Police Department says they feel they are perfectly confident and able to solve the murder cases.