Ray Abou-Arab, who was handcuffed and wearing a sleeveless smock, was arraigned in Toledo Municipal Court, appearing for the first time since he was charged on Friday with aggravated murder and arson.
Prosecutors and investigators revealed nothing new Monday about the fire, the arrest or a potential motive.
Abou-Arab, 61, was accused of using a flammable liquid to start the fast-moving fire that killed veteran firefighter Stephen Machcinski and rookie James Dickman, who were trapped inside in the apartment on Jan. 26.
An attorney representing the suspect did not comment on the charges or ask for a lower bond. Messages seeking comment were left at Abou-Arab's home and with his attorney.
Defense attorney James MacHarg did ask that police secure the scene of the fire until defense experts can examine the building.
About 60 firefighters and supporters, wearing red or black ribbons across their badges, marched as a group to the courthouse and packed the courtroom for Abou-Arab's first appearance since his arrest.
They turned silent when the suspect was led into court and several stared at Abou-Arab while he stood during the brief hearing. One firefighter held up a program from last week's memorial service for Machcinski and Dickman that had their photos on the front.
Toledo Fire Chief Luis Santiago said later at news conference that the arrest on Friday had unleashed negative emotions among firefighters. "It doesn't get any more personal," he said.
But he added that it was important to show restraint and respect the judicial system.
Santiago and Mayor D. Michael Collins would not answer any questions about what led to the arrest or the investigation, except to say the case was now in the hands of prosecutors.
Court documents filed Friday said Abou-Arab was in a garage at the site of the fire just before an apartment resident said she saw the blaze break out.
Radio calls from the scene of the fire indicated that the two firefighters faced rapidly deteriorating conditions once inside the six-unit apartment building near downtown. Firefighters found them inside, carried them out and tried unsuccessfully to save them.
Autopsies showed that Machcinski and Dickman died from burns and carbon monoxide exposure. No one else was seriously injured in the blaze.