Police say the original investigations into these deaths failed to identify the remains of Jane Doe and Janet Doe or determine a suspect.
New renderings based on Snapshot DNA Phenotyping of Jane Doe in May 2016 and Janet Doe in May 2017 gave detectives insight into the victims' features as well as genealogy.
In April 2018, detectives worked with the FBI to build the family trees of the women. They then compared the profiles of the victims against the Family Tree DNA database.
On January 29, 2019, the FBI gave the League City Police Department the results of those comparisons and were eventually able to identify and locate family members of those victims.
On Monday, police identified Jane Doe as Audrey Lee Cook. Cook was born on Nov. 25, 1955 in Memphis, Tennessee.
She lived in Channelview and Houston between 1976-1985. In 1979, she worked as a mechanic for a golf cart company in Houston. A year later, she worked for Harrison Equipment Company, also in Houston.
Cook worked for Balloon Affair in 1981. At some point, she worked as a mechanic for National Rent-A-Car.
Cook's family says the last time they heard from her was December 1985.
Cook was about 5'5" to 5'8" in height.
It's believed she was 30 years old, and she may have died six weeks to six months before her remains were found.
Janet Doe has been identified as Donna Prudhomme.
Prudhomme was born on April 23, 1957 in Port Arthur, Texas. Between 1982-1985, she lived in the Beaumont and Port Arthur areas.
In 1986, she moved to Austin. Two years later, Prudhomme moved to Seabrook and lived in an apartment complex.
She later lived in Nassau Bay, Texas in 1991. Police believe she frequently went to bars on Nasa Road 1.
Prudhomme was last seen in July 1991 and was believed to be 34 years old at the time of her death.
Analysis shows she weighed 100-130 pounds. Police believe she died six weeks before being found. She also appeared to have injuries to her upper spine that may have led to her death.
Authorities are now asking for the public's help to provide information about both women and hopefully, help find their killer. They are still actively investigating their deaths.
Neither of the women were officially reported missing.
Detectives have spoken to both women's families, who say they are going through a wide range of emotions knowing their loved ones have been found after being missing for so long.
WATCH: League City police give full details on victims
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"There's a reason this is called 'The Killing Fields,' there's a reason," said Tim Miller, the founder and director of Texas EquuSearch.
Miller started the organization after his daughter Laura was found dead in the same field in 1986.
"Laura was found right there and no grass has ever grown in that spot. No grass has ever grown where Laura's body was found," Miller said.
Laura, who was 16 at the time, was found on Feb. 2, 1986, just 17 months after she went missing from a nearby corner store. Investigators also found Jane Doe, who is Cook, the same day, lying nearby.
It's the same field, on Calder Road near I-45 in League City, where Heidi Fye was found two years earlier. For Miller, the thick brush became ground zero for his search to find their killer.
"I would come out here at 2 a.m. I would come out here at noon. I don't think there's an hour or a minute in the day at some time or another that I wasn't here. I wanted to see who was coming in and out. I was obsessed with this place," Miller said.
Some time after 1986, a man named Robert Abel leased the property in the area and opened Stardust Trailrides.
On Sep. 8, 1991, two people riding horses in the area of the rides found a fourth body, another unnamed woman they dubbed Janet Doe, who we now know is Prudhomme.
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"These girls deserve their names, they deserve their faces back," said Kathryn Casey.
The Houston-area author profiled the murders as part of her true crime book, "Deliver Us."
"I'm glad that they have their names now. That they're going to have their own picture and not a composite that was made off their skulls, that they're going to have a grave, that their siblings know what happened to their sisters, that their parents know what happened to their daughters," Casey said.
SEE MORE: A look back at women murdered while jogging
She's been following the cases since the 80s and conducted dozens of interviews as part of her research.
"It's not only that these girls have been identified, but knowing who they are might actually aid the investigation to help find their killer, or killers," said Casey.
Miller says this is the break, the lead they've always needed to find justice.
"I'm certainly hopeful this breaking news on who they are will move the investigation forward. That way we can go ahead and get the person that's responsible," said Miller.
Thirty bodies have been found in the so-called "Killing Fields" since the 1970s. Some murders have been solved and linked to serial killers. Others, including those of Laura Miller, Heidi Fye, Cook and Prudhomme, remain open.
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