SG also qualified the "we will pay" strongly with a request for "proof of life" even specifying we live in a time where videos and audio can easily be faked, etc. doesn't appear they ever got that and it dead-ended.
remember the initial ransom was based on some very thin "evidence" linking to the scene IMO, the location of an apple watch and which spotlight was broken?? someone could have theoretically hacked a police report etc. There was no distinguishing calling card left or something more typical. Many experts still can in the veracity of this supposed ransom note email