Only about 65 percent of homicides in the United States are solved -- down 15 percent from the mid-1970s -- but a new study led by a Michigan State University criminologist examines how some police departments are getting it right.

Departments that clear at least 80 percent of homicides tend to work closely with the community and other agencies such as the FBI and DEA. They adopt modern advances such as digital forensics and crime analysis. And they embrace the changing role of the homicide investigator -- from one who dug for information by "beating the pavement" in the past to one who manages a wealth of information from a network of people and online sources presently.

Bottom line: There is no silver bullet to reversing the steady decline in the homicide clearance rate, said lead author David Carter, MSU professor of criminal justice.

"The challenge is not simply to apply a new technology or implement a promising practice," Carter said. "Instead, we need to re-examine the role of the homicide investigator and the way they conduct homicide investigations. This includes changing some long-held homicide investigation policies that have been thought of as the Holy Grail."

The research project, which lasted four years, was funded by the U.S. Department of Justice and published in the May issue of the journal Homicide Studies.

Carter and colleague Jeremy Carter, assistant professor at Indiana University and an MSU graduate, studied metro areas that had at least 24 homicides and a clearance rate of 80 percent or better in 2011: Baltimore; Denver; Houston; Jacksonville, Florida; Richmond, Virginia; Sacramento, California; and San Diego.

The urban communities range in size from about 200,000 people (Richmond) to 2.1 million (Houston). Houston had the most homicide investigators, with 130, while Sacramento had the fewest, with nine. Homicide clearance rates ranged from 80 percent in Denver to 100 percent in San Diego.

These successful departments had a number of strategic similarities, including:

Assigning full homicide squads both during the day and evening, which led to faster response times.

Developing community trust, which is particularly important during interviews in the first 48 hours after a homicide.

Providing officers basic investigative tools and resources, including cell phone, camera, digital recorder, laptop computer and a take-home department car on days when the investigator was on-call.

A team approach also fueled better results. Successful homicide units worked with various external and internal departments, such as the gang unit during a gang-related homicide. In addition, patrol officers were trained to handle some investigative duties until detectives arrived. This runs in contrast to police departments that treat their patrol officers as simply "place holders" at a homicide scene.

"In successful agencies, patrol officers are viewed as partners in the investigation," David Carter said.

Ultimately, he added, successful investigation can prevent future homicides.

"Effective investigations can eliminate repeat offenders and reduce the number of retaliation homicides," the study says. "Although not the direct goal of homicide investigators, prevention can be an important artifact of a substantively strong investigation."