Police believe the suspect lives in the neighborhood. The shootings happened blocks from each other, within a span of about 36 hours.
WATCH: Surveillance video of Rogers Park murder suspect
Chicago police said 40 detectives are on the case, along with agents from the FBI and Bureau of Alcohol, Tobacco and Firearms.
"A lot of police activity," said Marina Zelinsky, a Rogers Park resident. "I've seen them in the parks time to time but not that much. Sheriffs and police cars all over the place."
Police will provide the latest information on the case and safety information at a 7:30 p.m. meeting at the Bernard Horwich JCC. At the meeting, the Jewish United Fund/Jewish Federation of Metropolitan Chicago will announce a $10,000 reward for information in connection with the killings.
Chicago police shared about a minute of surveillance video of the suspect. At one point the masked man is seen jogging down an alley. Police said he has a unique gait with his feet pointed out.
It was taken moments after 73-year-old Douglass Watts was gunned down on a sidewalk in the 1400-block of West Sherwin on Sunday morning. Just a day later, 24-year-old Eliyahu Moscowitz was also shot in the head and left for dead on the pedestrian path in Loyola Park.
"We all want answers," said Steve Loskutov, Moscowitz's friend. "We all want justice. It's sickening to think about it."
"Ever since this happened, I can't relax," said Brittany Findlan, a resident of Rogers Park. "If I'm outside, especially if it's nighttime. Yeah, it's tough."
Wednesday night, officers declined to talk about a motive for the shootings at a community meeting. Police have determined that both men were shot with the same gun.
"We have concerns about the people in this community and we're going to dedicate whatever resources we need to, to ensure that we find this guy and bring him to justice," said Chicago Police First Deputy Superintendent Anthony Riccio.
Anyone with information is asked to contact police.