UPDATED: 11/29/10 11:55 a.m.

CHICAGO (CBS) – Police credit neighbors with providing the information that helped them find a person of interest in the double murder of a fellow Chicago Police officer and a former Chicago Housing Authority officer.

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As CBS 2’s Dorothy Tucker reports, police are questioning the 19-year-old man at the Calumet Area Headquarters, 727 E. 111th St., and are calling him a person of interest in the Friday murders.

Officer Michael Flisk, 46, who worked as an evidence technician, and former CHA officer Stephen Peters, 44, were shot and killed Friday on the city’s Southeast Side. At the time, Flisk was investigating an early afternoon burglary in the garage at Peters’ mother’s home, in the 8100 block of South Burnham Avenue.

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As they investigated in broad daylight, someone apparently walked up and shot them both in the head. The victims didn’t even have a chance to get their own guns.

On Monday morning, black and purple bunting at Chicago Police Headquarters, 3510 S. Michigan Ave., signaled another day of grieving over yet another fallen officer. Bunting was also hung at Evidence Tech South, 6355 S. Wentworth Ave.

Peters’ mother believes whoever is responsible will be brought to justice.

“They’ll get him,” Laura Peters said. “They’ll get him.”

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While detectives searched for evidence, members of the Chicago Alternative Policing Strategy program passed out fliers and talked to neighbors.

CAPS is now headed by Officer Ronald Holt, who lost his 16-year-old son, Blair, to gun violence about three years ago.

Detectives believe Holt’s presence in the community prompted neighbors to open up.

They say the phone calls started pouring in on Saturday night, and that an anonymous tip led police to the 19-year-old person of interest.

He lives only a block from the crime scene.

Flisk joined the Chicago Police Department in January of 1991. He was assigned to the Evidence Technician Team – South unit for the past three-and-a-half years.

He received 67 awards during the course of his 19-year career. He earned 55 Honorable Mentions among many other notable achievements highlighting courageous and distinguished service. He has a wife and four children and has three siblings in the Police Department.

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Visitation for Flisk is 3 p.m. to 9 p.m. Tuesday at the Brady-Gill Funeral Home 2929 W. 87th St. in Evergreen Park. He will be buried Wednesday morning at Holy Sepulchre Cemetery in Alsip.