I remember that the detectives working on the Soham case in 2002 sent a voicemail to one of the missing girl's phones and then appealed on TV for their abductor to listen to the message. At the time this seemed like quite a strange thing for the detectives to do (people were a lot less savvy about phone evidence back then). It got a lot of coverage in the press.
In retrospect I wonder if it was a stingray-type gambit, whereby if the abductor turned the phone on they would be able to trace exactly where they were. I don't think it got mentioned in court so perhaps it was unofficial/inadmissable
You might be thinking of the murder of Milly Dowler. IIRC there was a scandal about reporters hacking into her voicemail, leading investigators to believe she might still be alive.
It's cool, but after reading up on the murders, it seems like they had already zeroed in on the suspect, and knowing the bodies were placed where they were when they were was not particularly impactful in the investigation - at the very least, the gamekeeper who discovered the bodies noticed a smell a few days before the discovery, and the remains were partially skeletonized, indicating that they had been there for a while.
Readit News
In retrospect I wonder if it was a stingray-type gambit, whereby if the abductor turned the phone on they would be able to trace exactly where they were. I don't think it got mentioned in court so perhaps it was unofficial/inadmissable
https://www.theguardian.com/uk/2002/aug/15/childprotection.c...
http://news.bbc.co.uk/1/hi/uk/3303637.stm
I guess the police and others didn’t know that at the time
https://www.bbc.co.uk/programmes/m0020qcs
https://www.bbc.co.uk/programmes/m000cz0p