Any information that a person in California puts online becomes public information. Even with security and privacy tools being used, this information is still available to anyone who really wants it, including, in many cases, law enforcement. In fact, the use of the internet, specifically social media, by law enforcement in the investigation of crimes has become rather popular. According to Small Business Trends, detectives are routinely using social media to gather clues and evidence to use against criminals in court.
Of course, there is a concern about privacy rights when law enforcement uses social media in investigations. In general, if a person posts anything to an online account, they lose the right to privacy for that information. This even includes information that was not published so it could be seen by the public.
Law enforcement may discover evidence of crimes in various ways. In some cases, people have posted about their crimes and gotten caught that way. Other times, law enforcement has gained legal access to an account to find information not otherwise publicly available. In addition, other people have turned in a friend or acquaintance who has posted about criminal activity. Officers have also created fake accounts and friended or followed suspects on social media platforms to try to gather information about alleged crimes.
Social media platforms have also put into place guidelines for cooperation with law enforcement who wants to gain access to an account. For example, Facebook has a post in its Safety Center for law enforcement that states it follows the federal Stored Communications Act in regards to disclosing any account records. Basically, this act requires a court order, subpoena or warrant that specifies the information to be released.