Detectives with the Chicago Police Department are working "round the clock" to find the slider that shot down an off-duty police officer, a official tweet on Sunday.
Officer John Rivera, 23, was shot and killed early Saturday, a few hours after he finished his shift and handled paperwork for a murder earlier in the night, police said. He was with another off-duty officer and two friends when a gunman opened fire on the car they were in, officials said Saturday.
One of Rivera's friends was also shot and wounded, police said. On Saturday, the police said the victim, an unidentified man, was in critical condition and undergoing surgery.
The actor and at least one other suspect remained on big Sunday.
But a spokesman for police force Anthony Guglielmi tweeted Sunday that investigators were working nonstop to find the killer.
"Investigators have been working around the clock to follow evidence and read dozens of camera feeds," Guglielmi wrote.
Case Update: investigators have been working 24 hours to follow evidence and read dozens of camera feeds. We continue to identify people of interest based on the study and we are talking to these people. pic.twitter.com/ryYog8ilBF
– Anthony Guglielmi (@AJGuglielmi) March 24, 2019
Eddie Johnson, the department's superintendent, said they would be poring over the network of cameras in downtown area where shooting took place.
"Mark my words," he said Saturday during a press conference, "we find them."
Rivera and the other officer who had just completed a "tour" left a nightclub with their two friends at 3:30 am on Saturday and returned to their vehicle, officials said. Two men approached their vehicle and one opened fire and killed Rivera and injured one of his friends.
The other off-duty officer and a woman with the group were not hurt, police said.
Chicago Police Department tweeted pictures showing a procession of police cars transferring officer's body to the physician's doctor's office.
An interested person was interviewed Saturday. Guglielmi said the detectives had identified other people.
"We continue to identify people of interest based on the study and we are talking to these people," he tweeted.
ABC News & # 39; Alexandra Faul and Olivia Rubin contributed to this report.