SAN DIEGO --

Deputy District Attorney Jeff Dusek, (pictured, right) lead prosecutor in the trial against David Westerfield for the murder of Danielle van Dam, has been chosen to lead a new cold case unit created to help solve more than 1,000 unsolved missing persons and murder cases within San Diego County.

District Attorney Bonnie Dumanis created the homicide unit which will begin operating in July.

DNA is the investigative tool of the new millennium. It helped seal the fate of Westerfield will be a primary factor in solving cold cases, 10News reported.

Take, for instance, the unsolved murder of Jonathan Sellers, (pictured, left), and Charlie Keever, (pictured, left).

A decade ago the two South Bay boys were assaulted and killed. Their murders baffled investigators for eight years and remained unsolved. The file was never closed until a DNA-analysis linked a convicted rapist to the murders. The suspect, Scott Erskine, stand trial for their murders this summer.

Solving cold cases is not just about closing the case or bringing the guilty to justice. It is also about bringing some type of closure to the victim's families, 10News reported.

Keever's mother, Maria Keever, appreciates the work the investigators have done however she knows that solving the crime will not make everything perfect again.

"Maybe when the trial is over (it will) give me closure. I did have peace after they found him. (I) don't think I'm ever gonna have (complete) closure, but it helps," Maria Keever said.

Dusek is excited about the challenge of tackling the cold cases.

"This seems to be best assignment in office for what I want to do -- chase down murderers and bring them to justice. I can't think of anything better to do," Dusek said.

Both the San Diego police department and the county sheriff's department already have cold case units. They will not hand over jurisdiction for their cases, but the district attorney's team will assist wherever appropriate, 10News reported.