Transcript for Fingerprints on Legos Help Police Make Arrest in Woman's Murder
a serious and rather strange note. We've got a story about a cold case cracked apparently thanks to a children's toy. Police in Utah say they've solved a decades old murder with the help of legos. ABC's aditi Roy has more. Good morning to you. Reporter: Good morning, Dan. It's the fascinating story. Investigators say it took them 23 years to catch a break in this cold case. The game changing clues, new DNA evidence and Lego toys found at the crime scene. Investigators say the fingerprints on these play things helped them bring charges in a decades long murder. The Lego bricks amonging to 78-year-old Lucille Johnson's grandson were found laying on the floor of her home where Johnson was hit in the head and strangled to death in 1991. She had many years ahead of her that we were robbed of. Reporter: Detectives learned from family members Johnson wouldn't just leave her grandkid's toys on the floor but the case went cold for decades. I wasn't sure that it ever would be solved. Reporter: Until last summer when DNA found from scrapings underer fingernails match that of John John Sansing on death row for unrelated murder. Occasionally we run into veries who evil. The individual that is being charged with this crime today can only be described as that. Reporter: Officials believe he used his 5-year-old son to befriend Johnson and her grandchild. Investigators say it was John Sansing's son's fingerprints found on the Lego toys. That child has been stormed with these visions all these years. Reporter: Detectives say this is how the case broke and her family a step closer to reaching their 23-year quest for justice. It's exciting to have answers after all of these years where we've just speculated and never known. Reporter: Investigators say San sing's wife will not be charged. San sing is currently on death row for muiring a woman in Arizona back in 1998. Dan. Such a strange case. Happy that family is getting answer, though. Aditi, thank you.
This transcript has been automatically generated and may not be 100% accurate.