MALTBY — A bulldozer was stolen early Wednesday morning from a work site near Highway 522 and driven into the base of a power-line tower, damaging it but not bringing it down. The FBI has taken over the investigation.

Anti-capitalism and radical environmentalist graffiti was spray-painted at the scene and on nearby structures, according to the Bonneville Power Administration, which operates the transmission line.

Service was not affected by the incident, said Mike Hansen, a BPA spokesman.

Snohomish County sheriff’s deputies secured the site after it was reported late Wednesday morning.

The case was handed over to the FBI because an important part of the regional energy grid was intentionally damaged and, based on the graffiti, the attack could have been ideologically inspired, said Ayn Dietrich-Williams, a spokeswoman for the FBI’s Seattle division.

The graffiti included the phrase “#killcap” — an anti-capitalism slogan — and “ELF,” the acronym for the extreme environmentalist Earth Liberation Front. The group has claimed credit or is suspected of being behind several attacks in Snohomish County in recent years. The incidents include knocking down two radio towers in 2009 near Snohomish, burning three model homes near Maltby the previous year and more arson fires around Snohomish and Monroe in 2004.

The 500-kilovolt power line connects two substations — Echo Lake and Monroe — and feeds local utilities, which provide power to consumers, said Hansen, the BPA spokesman.

Knocking down the tower could have started a fire and likely would have killed anyone in the immediate vicinity, but it wouldn’t have knocked out power, he said. “This was dumb for a lot of reasons.”

“There are redundancies built into the system. We can move power around,” Hansen said.

BPA crews are repairing the tower and were expected to be finished by Saturday.

Anyone with information about the attack can call the FBI at 206-622-0460.

Any tips could help, said Dietrich-Williams, the FBI spokeswoman.

“Maybe you heard something or saw a neighbor come home early Wednesday with spray paint on their hands.”

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.