Waiakea High School is continuing to deal with the effects of an April 2006 arson fire that caused $1.5 million in damage, as authorities consider charges against four teenage males identified as suspects.

Principal Kelcy Koga said the Big Island school and its 1,280 students are still in makeshift arrangements. Counselors who lost their offices now occupy a portable building, and the office has been moved to a space behind the library that was serving as a computer lab before the fire.

"We lost classroom space, and it's always to our disadvantage when you have to have to use classrooms for offices," Koga said Wednesday.

Construction to rebuild the damaged administration structure is expected to begin in October or November, he said.

The four males have not been arrested, but the arson case has been turned over to county prosecutors to file charges, said Lt. Randall Medeiros of the Criminal Investigation Division. One of the suspects is now 18; the others are 17.

Medeiros did not know whether they were students at the Hilo campus at the time of the April 11, 2006 fire.

Investigators determined that an accelerant was used to start the blaze in Building A, the administration building. A neighbor reported the fire at 1:15 a.m. The fire caused extensive damage to the registrar's and other offices and forced school officials to cancel classes for several days.

Police received a number of tips about the fire from the CrimeStoppers hot line and after the federal Bureau of Alcohol, Tobacco, Firearms and Explosives offered a $5,000 reward. Medeiros said the tips were helpful but detectives were able to nail down the case only after receiving information in the course of investigating a separate case earlier this year.

Smaller fires set Feb. 15 and April 5, 2006, caused minor damage to two portable classroom buildings at Waiakea High, but Medeiros said there isn't enough evidence to connect the four suspects to those arsons.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.