Legal Question in Business Law in California

Re: Partnership assets taken by one partner

Technically, an ordinaty citizen cannot file a criminal complaint; that is generally the province of the district attorney or attorney general. However, what is popularly called "pressing charges" often begins with a citizen victim of crime making a police report. Sometimes, the citizen can take the matter directly to the DA without first bringing the matter to the attention of the police or sheriff, but I think in most jurisdictions a formal report to the white-collar crimes staff of law enforcement is appropriate. Call a non-emergency police number and ask for advice as to what is appropriate in the jurisdiction.

Having said this, I would suggest you consider treating this as a civil matter instead of, or in addition to, a criminal offense.

Although you would have to pay a lawyer instead of having an assistant DA (maybe) handle the case, you would have a range of causes of action including conversion and breach of contract and fiduciary duty. You also need to think about withdrawing from this partnership and winding up its affairs. Even though you say "former" business partner, I'll bet there are a lot of loose ends and potential personal liability for you if the partnership is not wound up according to good practice.