It is likely that two cars, owned by prosecutor and former local police chief Gints Mežiņš and his wife, were intentionally set on fire July 16. Their sauna house also caught fire.
"The criminal police are working in an intensified regime. I have likewise ordered an intensive investigation and will be expecting a report on the results of the probe," Ģirģens told LETA news agency.
"This is an extraordinary case and people such as this should face stern justice," he said.
A criminal case has been started over the burning of Mežiņš' and his spouse's cars.
Two months ago a similar case happened in the peaceful town of Kuldīga in western Latvia, known for the stunning Venta Rapid waterfall.
Two cars owned by the family of businessman Roalds Cinis were set on fire in the old town amid suggestions that businesses were being squeezed by an attempted protection racket. The municipality gave CCTV footage to the State Police to aid the investigation.
Back then Inga Bērziņa, chairwoman of the Kuldīga Municipal Council, met Ģirģens and State Police head Ints Ķuzis to discuss the way a speedy investigation could be carried out.
"A new case of arson in Kuldīga municipality has caused great worry and anxiety among the locals. The municipality will repeatedly turn to the Interior Minister and head of the State Police to ask for a thorough investigation with the goal of quickly identifying and calling to justice the perpetrator of this criminal act," she said.