The Spanish National Court has charged the former head of Catalonia's regional police and other security officials with sedition over their role in events leading to a banned referendum on independence from Spain.
Judge Carmen Lamela said in an indictment that Mossos d'Esquadra chief Josep Lluis Trapero was part of an organised plan to seek Catalonia's secession, which courts have forbidden as the Constitution says Spain is "indivisible".
The indictment is another legal blow to those in the region who nurture hopes of creating a new country.
Spanish courts have repeatedly blocked moves towards independence and brought charges against its supporters.
Mr Trapero was hailed in Catalonia as a local hero for the handling of deadly extremist attacks in and near Barcelona last summer.
But he then came under severe pressure when Spanish national authorities asked his regional police force to help prevent the outlawed October 1 referendum, which triggered Spain's worst political crisis in decades.
Mr Trapero quit the force in October after being demoted when the Spanish government imposed direct rule on the region. Two other members of the regional police and an official from the regional interior department were also indicted on Thursday.
In a separate political development, former Catalan separatist leader Carles Puigdemont sent an open letter from prison in Germany urging Catalonia's parliament to make another attempt to elect jailed separatist activist Jordi Sanchez as the region's president.
Mr Puigdemont also proposed Mr Sanchez - his deputy in the Together for Catalonia party - last month, but Spain's Supreme Court refused to free him to attend a parliamentary session. Another attempt would keep the independence issue politically alive.
The separatist majority in Catalonia's regional parliament had wanted to elect Mr Puigdemont as Catalan president, but he fled to Belgium to escape arrest in Spain on rebellion charges for his role in last year's push to secede. He was detained in Germany last month after entering from Denmark.
Mr Sanchez said in a letter from his Madrid jail that he was ready to try again to be elected.