(CNN) -- A police officer jailed on a first-degree murder charge in a two-state shooting rampage was on his computer at the time of shootings and could not have committed them, prosecutors said Tuesday evening.
Brian E. Dorian, 37, was to be released on his own recognizance Tuesday night, and charges against him will be formally dismissed Wednesday, Will County State's Attorney James W. Glasgow announced.
"I feel horrible that Brian Dorian went through this," said Glasgow, adding that evidence at the time and identification in lineups merited the charges. "At no time did we stop looking for exculpatory evidence."
A forensic analysis of Dorian's home computer and its activity put Dorian at home at the time of the shootings, authorities said. The officer also told them he was watching sports programs and using e-mail.
John Dorian, the officer's father, told CNN affiliate WLS he was "relieved" and "never doubted his son."
Police now are looking at other leads in the shootings.
Earlier in the day, Dorian appeared in court via a hookup from the Will County Jail. He did not speak but his attorney entered a not guilty plea, WLS reported.
Several friends and relatives wore T-shirts bearing the message "Free Brian."
"There's an innocent man sitting behind bars and somebody else is running around out there knowing that he got away with it. It's not fair," Jill Aggen, a friend of Dorian, told WLS. "No doubt in my mind. He's not capable of it."
Dorian, an officer with the Lynwood Police Department, was arrested Friday in the killing of one person and the wounding of three others in the spree, which occurred south of Chicago, Illinois.
He was held on a probable cause warrant, and bail was set at $2.5 million.
Dorian, who according to WLS has been on medical leave for an injured shoulder the past year, was taken into custody Friday at his residence, said authorities.
The shootings began about 10:30 a.m. October 5 at a construction site near Beecher, Illinois. The gunman killed one worker at the site and wounded two others, police have said.
An hour later and about 10 miles away in Lowell, Indiana, authorities believe the same gunman opened fire again -- this time on a local farmer. Keith Dahl was shot in the left shoulder, arm and elbow, and then was robbed.
Dahl told Lake County (Indiana) Sheriff's Detective Robert Martinez that the gunman approached him on his farm and started a conversation about bees before beginning to shoot.
The gunman was believed to be using a revolver -- possibly a Colt .38-caliber or .357 Magnum -- because no shell casings were found at either scene, Lake County Sheriff Rogelio "Roy" Dominguez said.