Lego Fingerprints Helped Solve Cold Case Murder Suspect may have brought young son as distraction to crime, cops say.

 -- Fingerprints found on Lego building blocks helped police crack a 23-year-old cold case murder mystery in Utah, authorities said.

The gruesome murder of 78-year-old Lucille Johnson in Salt Lake City left police puzzled in 1991.

The grandmother was strangled and beaten in her home and police found Legos in the entryway of her living room and driveway the floor, but were unable to discern who killed her, the Salt Lake Sheriff's Office said.

When the case was reopened last year, investigators tested the residue found under Johnson's fingernails for DNA and found that it matched that of 47-year-old John Sansing, a convicted murderer serving a prison sentence in Arizona for an unrelated case, Lt. Justin Hoyal of the Sheriff's Office said today.

They also tested the fingerprints on the Legos found at the scene and found that the prints matched that of Sansing's son.

Police said Johnson and Sansing did not know each other and were investigating whether Sansing used the child to gain entry to the house.

"We know there's no relationship between the two of them,'Hoyal said. "It's speculative as to whether the child was a ruse that was used, but it's certainly a possibility."

Police don't know have a motive for the crime but said that Johnson's ring and necklace were missing, Hoyal said. They also said that Sansing is believed to have brought his son to the Arizona murder scene as well.

Sheriff Jim Winder announced at a press conference Thursday that Sansing had been charged with capital murder in Utah for the crime, according to ABC News affiliate KTVX.

“Occasionally we encounter people who are evil,” Winder said. “The individual who perpetrated this is nothing short of that.”

“It was very important that it be solved,” Jerry Johnson, Lucille Johnnson's son, told KTVX. “I wasn't sure it would ever be solved.”

“I am so grateful, so very grateful to the police department for the work that they’ve done,” Johnson's daughter, Shirley England, told KXTV. “I don’t think closure is the right word because you never close something like this. It’s been a terrible thing in our life.”

The Sheriff's Office had no information on if or when Sansing would be extradited, when Sansing would appear in court, or who his lawyer would be. The District Attorney has not yet responded to calls for comment.