A few weeks after the Justice League learned of 'The Phantom' a Justice League compound was attacked by Earth First. The league officers who were guarding the facility were overwhelmed and were forced to retreat. Two officers, 'Steel' and 'Ice', were killed in the attack.
The facility had been used to house metahuman prisoners who the league considered to be too dangerous for Stryker's
After the attack, the Justice League determined that some of Dr. Jeff Palmer's lab equipment had been stolen. Their suspicions about Jeff were confirmed. He was the 'The Phantom', as they had suspected.
Greg was devastated. He set out to find Jeff himself. He discovered that Jeff emitted a rare form of radiation when he was invisible, and began searching for him.
He eventually tracked Jeff down to a lab in
Jeff yelled back at Greg, asking him for a chance to explain himself.
Greg told Jeff that he was taking him into custody and that Jeff would answer for his crimes. He flew toward him.
Jeff pulled out a weapon and fired. Greg fell to the ground, unconscious. Police later found him in an alley. He was in a coma-like state.
(Note: The picture in the middle is Rorschach from the movie 'The Watchmen' as Jeff Palmer/The Phantom)