Police investigations pointed towards the suspect on the basis of witness descriptions and the odd behaviour his colleagues picked up on during the forest fires period.
It remains unclear why the 30-year-old officer decided to cause 19 forest fires in the Madrid municipalities of Navas del Rey, Chapinería and Cadalso de los Vidrios.
According to a police statement, the suspect would light the blazes at times when the flames would spread faster through the woodlands.
Witnesses told Spain’s Civil Guard they spotted a man on a bike on Juy 17th riding through forest paths and starting up to four fires.
If found guilty, the officer faces a maximum five-year jail sentence and a fine of up to €216,000.