(NewsNation) — NewsNation senior national correspondent Brian Entin spent time in tunnels and abandoned houses near Portland, Oregon, looking for answers about a potential serial killer.

After more than a year, authorities may be closing in on a person of interest in the slayings of four Portland women, killings that terrorized the Oregon city. Five women, all younger than 35, were found dead over three months in 2023. After initially saying the murders were unrelated, police later concluded four of the deaths were linked.

The victims included Kristin Smith, found in a field Feb. 19, 2023; Charity Perry, discovered near a state park April 24; Bridget Webster, found April 30; and Ashley Real, located in a rural area May 7. The medical examiner determined blunt force trauma as the cause of death for 32-year-old Joanna Speaks, whose body was discovered in a rural area. Police have not tied Speaks’ death to the other four women.

A person of interest in connection with the killings, Jesse Lee Calhoun, is jailed on a parole violation and could be released next month. The convicted felon had his sentence commuted in 2021 by then-Gov. Kate Brown for helping battle wildfires while imprisoned for burglary, car theft and assaulting an officer.

Diana Allen, the mother of Perry, told Entin she thinks her daughter was intentionally “placed” near the state park, where her body was discovered.

“I don’t think she died here. I think she was placed,” Allen said. “She wasn’t a person who drove. I was given enough detail to know there was no way she walked here. And she didn’t have shoes. So besides it being cold, they would have been able to tell that she walked here,” Allen said.

“I know that (the killer) worked really hard to hide her,” Allen added.

Smith’s mom, Melissa, told Entin she had “scoured the whole property” where her daughter’s body was found. Additionally, some witnesses reportedly saw Calhoun in the same area.