CHICAGO (CBS) — Community activists in Rogers Park are asking the Guardian Angels to help kids safe while trick-or-treating on Halloween, as police search for the killer in two unsolved murders.

Douglass Watts, 73, was shot and killed on Sept. 30 while walking his dogs. About 36 hours later, 24-year-old Eliyahu Moscowitz was gunned down about a half mile away.

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Douglass Watts (left) and Eliyahu Moscowitz (right) were shot and killed blocks apart in a span of about 36 hours, and police have determined both men were killed with the same gun. (Photos supplied to CBS)

Police have released surveillance video of the suspect, showing him dressed in all black, with a mask covering his face.

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No one has been arrested as of Monday morning, and some neighbors are concerned the masked killer could strike again on Halloween, by blending in with people wearing costumes.

Chicago police say this man is a suspect in the fatal shooting of 73-year-old Douglass Watts on Sept. 30, 2018. Ballistics tests have linked the shooting to another homicide one day later, the slaying of 24-year-old Eliyahu Moscowitz. (Credit: Chicago Police)

Some Rogers Park residents want the Guardian Angels – an unarmed volunteer group – to patrol the neighborhood on Halloween.

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A total of $23,000 in reward money is being offered for information leading to an arrest in the two murders.