Nick Willick used to be the chief of the Auburn Police Department. He fired DeAngelo from the force in 1979 for stealing dog repellant and a hammer. Willick said DeAngelo later filed a lawsuit against the department.
"The investigator told me that Joseph had gone to my house one night to kill me, and said that he walked around the house looking in the windows but couldn't find my bedroom," Willick said. "I just never saw him as a person who could, you know, kill somebody."
VIDEO: Tracking Joseph James DeAngelo and the 'Golden State Killer'
Willick gave his account during an interview that aired on "Good Morning America" Thursday.
"A short time after he had been fired, I woke up one morning. My 4-year-old daughter was laying alongside the bed. She said, 'Dad, last night there was someone looking in my bedroom window with a flashlight,'" Willick said.
Willick said he feels guilt and embarrassment over the fact that a suspected serial killer was right under his nose, and he slipped away.
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"I just wish we, it could have, you know, been stopped a long time ago," Willick said.
The former police chief also said years ago, DeAngelo once gave him a tour of his home, explaining that he and his wife slept in separate bedrooms. Willick said he wondered if that living arrangement may have enabled DeAngelo to sneak out of his house in the middle of the night.
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DeAngelo , 72, is expected to appear in a Sacramento courtroom Thursday to fight prosecutors' efforts to collect more of his DNA.
His public defender, Diane Howard, has filed a motion to block efforts by the district attorney to take DNA, fingerprints and photos of DeAngelo's body. Sacramento County District Attorney Anne Marie Schubert got a warrant last week to gather the samples and photographs.
DeAngelo was arrested last week and identified as the suspect in at least a dozen murders and more than 50 rapes between 1976 and 1986.
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Prosecutors had planned to take more DNA and photographs on Wednesday, prompting Howard's motion to halt the action. In a brief court appearance, Superior Court Judge Michael Sweet delayed the hearing until Thursday.
Howard argued in a motion that the search warrant should be stopped because it was approved before DeAngelo was arrested and arraigned last week.
Prosecutors argued that the search warrant was still relevant and said collecting the evidence won't be "testimonial in nature."
DeAngelo has not yet entered a plea.
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The Associated Press and ABC News contributed to this report.