The federal government opened a criminal investigation into deputies who used liquid pepper spray on the eyes of anti-logging demonstrators.
A Justice Department spokesman said Friday that the FBI had begun a preliminary inquiry to determine if criminal civil rights violations took place.
Such an inquiry, under the same laws used in the Rodney King case, can lead to prosecution and imprisonment of law enforcement officers, the spokesman said.
Nine anti-logging protesters sued the Humboldt County Sheriff's Office Thursday, saying they were subjected to excessive force when officers broke up their sit-ins by putting liquid pepper spray in their eyes with cotton swabs.
Videotapes made by the Sheriff's Office and played Thursday by the protesters' lawyers show demonstrators screaming as deputies pulled back their heads to apply the burning substance. At least one woman had the substance sprayed into her eyes.
The spraying took place at Pacific Lumber Co. headquarters in Scotia on Sept. 25 and at Rep. Frank Riggs' Eureka office on Oct. 16. The protests were aimed at the company's logging old-growth timber and a proposed federal settlement of a dispute over the Headwaters Forest.
At the sit-ins, the protesters joined hands inside a metal sleeve, to which they were fastened by small chains. Their lawyers said deputies had used a metal-cutting machine in the past to cut through the sleeves.