On November 20, 1994, at approximately 12:30 p.m., Lawrence was found stabbed to death inside her home, Fairfax County Police said. Her two-year-old daughter was found alone in another room of the house unharmed. The nearly 30-year-old case was solved, police said, using genetic genealogy analysis over three years.

Detectives say after coincidentally arriving at his house as Smerk was taking out his trash, they obtained a consensual DNA sample from him and later a "full confession" to the crime. Smerk, who was on active duty in the Army, was living at Fort Myers in the Northern Virginia suburbs of Washington D.C., police said.

"He chose her seemingly randomly, and it was a heinous, heinous scene. And I've seen a lot of crime scenes in person and photographs of one, and this one was particularly gruesome," Fairfax County Police Chief Kevin Davis said.

Smerk had no prior arrest record before being taken into custody this month, and police say there’s no reason to believe he was suspected of any similar crimes. Smerk had no connection to the victim, police said. He’s currently in custody in New York and is awaiting extradition to Virginia. ABC was not immediately able to locate a legal representative for Smerk.

"We as the family who's sitting here to my left would like to thank the Fairfax and Niskayuna police departments for their work on this case. We look forward to learning more about the process and next steps," Lauren Ovans, a cousin of the victim told reporters on Monday,

DNA testing

Police collected DNA from the 1994 crime scene and created a DNA profile that had no matches, which was uploaded to the national database for DNA. The use of the genetic genealogy analysis helped break the case after cold case detectives submitted that DNA to Parabon NanoLabs, a Virginia DNA technology-based company, police said.

The police force was able to develop "a profile using that DNA and began searching genealogical databases. They use that information to develop a family tree which they provided to our detectives and a volunteer who worked with our cold case detectives,” said Fairfax Police Deputy Chief of Investigations Eli Cory.

Investigation and confession

Before traveling to New York, Fairfax County cold case detectives say they compared the composite sketch to Smerk's high school yearbook picture and a DMV picture of him in the 1990s.

Detectives then went to Niskayuna, New York, and arrived at Smerk’s house. Detectives say they talked to him and Smerk willingly agreed to an additional DNA swab, authorities said. Police said that Smerk’s willingness to cooperate was “highly unusual, so that was a clue to our detectives that something may be afoot," Chief Davis said.

The Fairfax County cold case detectives left and were preparing to return to Virginia when they say Smerk called and told them, "I want to talk and I want to talk right now," police said. Detectives advised him to call 911 and go to the local police station, according to police.

Smerk, who is now a software engineer, "fully described his involvement. It is beyond involvement, he talked about killing Robin. And he talked a little bit about some more details that I won't go into, but it was a full confession. And it was a confession with more than enough details. Coupled with the genetic genealogy research," Chief Davis said on Monday.

Fairfax County Police say they have been in contact with the Army however, they believe Smerk will be prosecuted in the county.

"The evidence that we have the strength of this case is overwhelming. And we feel fully comfortable that he's going to be successfully prosecuted right here in Fairfax County," Chief Davis said.