‘Pinging’ a criminal suspect’s mobile phone to reveal the suspect’s real-time location is a search under the Massachusetts constitution, the state’s top court ruled in a murder case.

Jerome Almonor was suspected of murder. The police had his mobile service provider ping his phone, which helped them identify his likely location. Police entered that address with the consent of the homeowner and arrested Almonor. They later obtained a search warrant for the room he was found in, and seized a...