When a cellphone is reported stolen in New York, the Police Department routinely subpoenas the phone’s call records, from the day of the theft onward. The logic is simple: If a thief uses the phone, a list of incoming and outgoing calls could lead to the suspect.

But in the process, the Police Department has quietly amassed a trove of telephone logs, all obtained without a court order, that could conceivably be used for any investigative purpose.

The call records from the stolen cellphones are integrated into a database known as the Enterprise Case Management System, according to Police Department documents from the detective bureau. Each phone number is hyperlinked, enabling detectives to cross-reference it against phone numbers in other files.

The subpoenas not only cover the records of the thief’s calls, but also encompass calls to and from the victim on the day of the theft. In some cases the records can include calls made to and from a victim’s new cellphone, if the stolen phone’s number has been transferred, three detectives said in interviews.