I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Once police get a subpoena and serve it on a company, they have 30 days to respond by producing the documents. To get a subpoena, they need to go through the district attorney, which can take a few days depending on the case load the DA is dealing with. Once they get it, since you're not in the same state where Craigslist is located, then they need to talk to a district attorney or US Attorney in California to help them file the subpoena and get one issued by the court in the other state. That, unfortunately, can take a few weeks.
The process is more or less the same for dating sites. Police need a subpoena that is issued by the courts in the state where the company is located. If you're dealing with the FBI, it can be a little faster, because they're already in place in every state. Police can also subpoena cell phone records if she's calling/texting you, and that's the same process.
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