CHICAGO (CBS) — Two men were shot and killed in less than two days in Rogers Park, just blocks away from each other, and police believe one gunman is responsible.

Chicago police said ballistics tests show the same gun was used in both slayings, leading investigators to believe one suspect shot both victims.

Eliyahu Moscowitz, 24, was walking down the bike path on the 1100 block of West Lunt Avenue around 10:20 p.m. Monday when someone shot him. The 24-year-old was an Orthodox Jewish man who worked at an Evanston Jewel. Friends gathered for a vigil Tuesday night as they mourned the loss of their neighbor.

eliyahu moscowitz Chicago Police Link Two Fatal Shootings In Rogers Park To Same Gun

Eliyahu Moscowitz, 24, was shot and killed while was walking down the bike path on the 1100 block of West Lunt Avenue on Oct. 1, 2018. (Photo supplied to CBS)

The shooting happened about half a mile away from where 73-year-old Douglass Watts was shot and killed while walking his two dogs Sunday morning in the 1400 block of West Sherwin.

douglass watts Chicago Police Link Two Fatal Shootings In Rogers Park To Same Gun

Douglass Watts, 73, was shot and killed while out walking his dogs on Sept. 30, 2018. (Photo supplied to CBS)

Both victims had been shot in the head, and Chicago Police Supt. Eddie Johnson said Tuesday afternoon that ballistics tests confirmed shell casings from both shootings came from the same gun.

“Given the frequency of these homicides, and what we know about the investigations, detectives have been working aggressively to cultivate leads,” Johnson said.

Investigators have enlisted the help of the FBI and ATF, and are checking surveillance video from private businesses and CTA buses in the area.

rogers park gunman Chicago Police Link Two Fatal Shootings In Rogers Park To Same Gun

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)

Police have released a surveillance image of the suspect, who is wearing a black cap or hood and a black mask over the lower half of his face. He is also seen wearing a black jacket, black pants, and black shoes or boots.

“I can assure you the person or persons responsible will be brought to justice,” Johnson said. “The way we will do it is by working together. There is someone out there who knows who this person is, whether it’s a family member, a friend, or a trusted loved one, we need you to do the right thing and call the police.”

Johnson said police also will saturate the Rogers Park area in response to the shooting, particularly along the lakefront. Gang teams and tactical teams also will be deployed in strategic areas.

“Our priority is to ensure the safety and security of everyone,” Johnson said.

Mayor Rahm Emanuel expressed his condolences to the victims’ families.

“Their deaths were senseless and tragic. As a city, our hearts especially go out to their families whose own lives have been torn apart,” he said.

“People are extremely upset. People are scared,” said Fallon Sowers, a Rogers Park resident.

“I hate feeling like I can’t trust a person that’s walking down the street,” agreed G. David Drury, a neighborhood resident.

Police have said anyone with information about the shootings should call Area North detectives at 312-744-8200.

Police said they are hoping to ease community fears by beefing up foot, bike, and squad patrols across the north side neighborhood until further notice.

Residents are invited to hear updates on the investigation at a 7 p.m. meeting Wednesday at the Loyola Park Fieldhouse.

CBS 2’s Lauren Victory and Mai Martinez contributed to this story.