I was rewatching a documentary about Delphi, it's free to watch on Roku.
It's also on a lot of streaming channels like MAX, Apple TV, Hulu, Amazon, Sling etc...
It's called...
Down The Hill:The Delphi Murders a HLN(CNN) two part documentary.
On Part One of the documentary is where the overnight search for the girls is discussed.
At 1:30am the fireman Sterrett had talked to the Sheriff to tell him he wanted to send his volunteers home, they all had to go to work the next day and had been searching for hours.
At 15:35 in video fireman Sterrett said at 2:30am he got a call back from the Sheriff. The lastest phone ping to the cell tower was giving a location in the area of the Monon High Bridge, come down with some lighting.
BP stated she had [previously] at 1:30am begged them not to stop searching as it was getting cold out. At around the 15:46 in video, BP says "Mike says they're not stopping".