Raymond Oyler had been detained in connection with two counts of arson relating to wild fires in June.
He was described by police as a "person of interest" in an October 26 blaze that destroyed 54 homes and charred thousands of hectares after it erupted in Riverside County, about 200 kilometres east of Los Angeles.
Police say they believe Mr Oyler started the fires which killed the firefighters in Esperanza.
"We recommend that the district attorney charge Mr Oyler with the five murders of the United States Forest Service firefighters along with 11 counts of arson," said Riverside County assistant sheriff Neil Lingle.
Four firefighters died at the scene when flames engulfed them as they battled to beat back flames bearing down on a home, while the fifth died in hospital on Tuesday after suffering 90 percent burns on his body.
The deaths prompted authorities to offer a $US500,000 ($A645,000) reward.
If convicted Mr Oyler could face the death penalty.
"In the next 60 days our office will make its determination whether or not to seek the death penalty against the suspect and soon-to-be defendant but only after a careful and sober review of the evidence," District Attorney Rod Pacheco said.
Mr Pacheco said the feelings of the dead firefighters' families would be taken into consideration as prosecutors mulled whether or not to press for the death penalty.