The killing in Martinez happened less than a month before the Stoner killing in 1987. The victim was 9-year-old Eric Coy.
The boy was killed after leaving to go to his cousin and best friends house in Martinez, California.
"The boy was brutally murdered after leaving his house, stabbed with a blunt object," said one ABC7 News report in 1987.
"For the last two days, that play site has been a grim searching zone for police," said another ABC7 News report days later.
EXCLUSIVE: Suspected child killer in 1987 Vallejo cold case arrested. 'I hope he rots in Hell'
EXCLUSIVE: Suspected child killer in 1987 Vallejo cold case arrested
No one was ever convicted of the killing but now, less than a week after prosecutors say they used DNA to link Cain to the murder of Stoner, authorities in Martinez are taking notice. They're working with the Solano County District Attorney's office to learn more about Cain, and if he could also be linked to Coy's murder.
"Is he an official suspect in the case?" asked ABC7 News reporter J.R. Stone.
"Right now, he is a person of interest," replied Lt. Patrick Salamid.
Salamid has spent the last 11 years working Coy's case.
"Left his house on Warren Street and took a short cut through Martinez Junior High, within about 15 minutes his body was found on the grounds of the Junior High. They found that Eric Coy had suffered multiple stab wounds," said Lt. Salamid.
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Cain's family members, who ABC7 News spoke with Wednesday night, say they don't believe Cain lived in Martinez at that time, but say he did live in the nearby East Bay town of Pacheco.
In Coy's case, there was a suspect sketch but it never amounted to anything. The boy's body was found near a pedestrian bridge that is no longer there today, as the area is now overgrown with ivy.
As for the case going forward-
"I'm always optimistic, and maybe some DNA or some biological evidence will exist in the future, whatever they reanalyze but I can tell you we're not going to stop investigating this case,"
Law enforcement transferred Fred Cain III from Oregon, where he was arrested, to California on Wednesday.
He will face a judge for the first time in Solano County on Thursday at 1:30 p.m.