(CNN) -- Police in Omaha, Nebraska, said Friday they are checking into whether two cases of double homicide -- separated by six miles and five years -- may be linked.
All four victims had ties to the pathology department at Creighton University Medical School.
The comparisons arose Tuesday, when Roger and Mary Brumback, both 65, were found dead inside their Omaha home.
Roger Brumback was a professor in the pathology and neurology departments at Creighton University.
After 12 years at Creighton, where he had served as chairman of the Department of Pathology, Brumback had recently announced he would retire next month and move to West Virginia.
When a piano mover arrived Tuesday at the house, he found an ammunition clip wedged in the doorway and Mary Brumback's body inside, police said.
On March 13, 2008, 11-year-old Thomas Hunter and his family's housekeeper, Shirlee Sherman, were found dead in the Hunters' home in Omaha, according to the FBI.
The boy's father, Dr. William Hunter, was then and is still faculty member in Creighton's 12-person pathology department. He did not immediately return a call from CNN, but he told the Omaha World-Herald that he wondered if the same person could have been responsible.
"It's just a thought that comes by," he told the newspaper.
His wife, Dr. Claire Hunter, an associate professor in Creighton's cardiology division, also did not immediately return a call.
A cold-case unit is assisting to determine whether there is a connection between the cases, police said.
Brumback's colleagues "described him as a perfectionist who was very popular with his students and other faculty," the school said on its website.
"When I heard the news last night, I was literally shaken," Laura Neece-Baltaro, a friend of the Brumback family, told CNN affiliate KETV.
She met them when they all lived in Oklahoma in the 1990s.
"Why would anyone want to harm them? They did so much for the community here, and the community in Oklahoma City and they were still contributing. They still had a lot to give back," she said.
"It's a terrible loss to the whole world that they're no longer with us."
A prayer service was held Thursday at the school for the couple. Students wore white coats in tribute.
"It's just kind of shocking to have somebody that seemed so full of life and invincible taken so suddenly," said Creighton medical student Justin McCarthy, KETV reported.
CNN's Kyung Lah contributed to this report