Brent Robert Kastroff, 62, is accused of setting one of the fires last year -- and then starting two more fires this year.
Kastroff reportedly admitted to burning papers on small spots of grass on a property next to his home. Although the fires were quickly extinguished -- fire officials say the damage could have been far worse.
"He was lighting grass and trash in an area that had a very high potential for very serious wildfires and the earliest fire we documented was in May of 2011, which would be in the beginning of the wildfire season," said Vic Massenkoff, a Contra Costa fire investigator.
Kastroff was arrested in 1998 for setting a fire in a San Rafael trash can. Investigators say he may be responsible for setting as many as nine fires in the Walnut Creek area.