The murders of the women, named Jane Doe and Janet Doe, were part of a larger murder mystery known locally as the "The Calder Road Murders" or "The Killing Fields," involving four women in total, according to authorities.
The first body was found on April 6, 1984, when the family dog of Heidi Frye brought her skeletal remains to her home on Ervin Street in League City, Texas, League City Police Chief Gary Ratliff told reporters at a news conference Monday. Frye had been reported missing on Oct. 10, 1983, when she was 25 years old. The rest of her remains were located in a wooded area near the home, Ratliff said.
The second body was found on Feb. 2, 1986, by two juveniles who were riding bikes in the same area where Frye's body was discovered on Calder Road, Ratliff said. As investigators processed the scene, another body was found in close proximity but they were in "vastly different stages of decomposition," Ratliff said.
The second body was unable to be identified, so the medical examiner named the remains Jane Doe, Ratliff said. Officials were able to identify the other body as Laura Miller, who was reported missing on Sept. 24, 1984, when she was 16 years old. Officials used dental records to identity her remains.
Sometime after 1986, an area nearby was leased for recreational horse riding, Ratliff said. Two people riding horses in the area in September 1991 found the fourth body, which was given the name Janet Doe by the medical examiner, Ratliff said.
A connection between all four murders has not been determined yet, other than the location of where their remains were found, said League City Police Lt. Michael Bluffington.
Authorities are now seeking the public's assistance to find out more information about the women before the time of their deaths. Several persons of interests have been identified but authorities currently do not have enough to officially name anyone as a suspect, Bluffington said.
"We want to compete the investigation," Bluffington said. "At this time, we really just want to focus on these girls, who they were, the people that knew them and that’s kind of where we wanna steer this today."
Jane Doe identified as Audrey Lee Cook
Audrey Lee Cook was born on Nov. 25, 1955, in Memphis, Tennessee, and lived in Houston and Channelview, Texas, between 1976 and 1985, Ratliff said. She was estimated to be about 30 years old at the time of her death.
Cook moved to the Houston area with her girlfriend at the time to establish "a new life," Bluffington said. She regularly communicated with her parents via letters and phone calls and when they hadn't heard from her in a while, they traveled to Houston to search for her, Bluffington said.
In 1979, she was working as a mechanic for a golf cart company in Houston, later getting a job at the Harrison Equipment Corporation, a construction equipment company, Ratliff said.
At some point she started working for National Rent-A-Car but the dates of her employment are unknown, Ratliff said.
Associates of Cook also reported to authorities that she possibly sold and used cocaine, Ratliff said. She and her girlfriend had broken up at the time of her disappearance, Bluffington said.
Janet Doe identified as Donna Prudhomme
Donna Prudhomme was born on April 23, 1957, in Port Arthur, Texas, and was estimated to be about 34 years old at the time of her death, Ratliff said. Between 1982 to 1985 she lived in the Beaumont-Port Arthur area, moving to Austin in 1986, Ratliff said.
In 1988, she moved to the Seabrook, Texas, area, where she lived in several apartment complexes. She also lived in Nassau Bay, Texas, in 1991, Ratliff said. She was last seen in July 1991.
Authorities currently do not have any information about Prudhomme's employment, Bluffington said, adding that she was a "frequent patron" of several of the local bars in the Seabrook and Nassau Bay areas.
Prudhomme "just kind of fell out of contact with her family," Bluffington said. Her sister knew she was living in the Seabrook area and the two had communicated a few times by mail. But "they just kind of lived different lives," Bluffington said.
The purpose of one of Prudhomme's moves was to escape an abusive relationship and she arranged for her two sons live with their grandparents, Bluffington said.
Only one of her sons is still living. When investigators spoke to him, he told them he "kind of thought his mom just moved on."
How they were identified
League City Police detectives "worked diligently" since the bodies were discovered to identify Jane Doe and Janet Doe, Ratliff said.
In 2016, the department learned of Parabon NanoLabs, a Virginia-based company that provides DNA phenotyping for law enforcement, Ratliff said. The skulls of the unidentified victims were taken to Texas State University, where 3D composites were printed.
After the phenotyping was completed, investigators began working with GenMatch to use genetic genealogy to compose family trees for both of the victims.
Once the family trees were completed, authorities were able to locate the son and sister of Janet Doe and coordinate DNA collections for family members of Jane Doe that were out of state.
After the DNA comparisons were conducted from family members, positive matches were made, Ratliff said. The medical examiner agreed with the results and is now in the process of amending the death certificates, Ratliff said.
The families are now undergoing a "formal grieving process" now that they know "that their loved one is actually deceased, not just missing or living a new life somewhere," Bluffington said.
ABC News' Stacy Chen contributed to this report.