Shamshak said investigators are also planning to re-interview Stanger in his prison cell on Thursday at the Union Correctional Institution in Raiford, Fla.
Coincidentally, Thursday would have been Bish's 29th birthday.
"I said to Magi Bish, 'I hope there is a present and some closure tomorrow,'" Shamshak said.
Molly's sister Heather said she hopes that the truth will come out as a result of investigators' efforts in Florida.
"[Police] initially said in the investigation that we were missing pieces of the puzzle, but I think we're in reach of those pieces," she said.
"If the person who did this could have a change of heart and tell us what happened, it would give us a certain amount of peace and closure, just as far as justice is concerned," said Heather Bish.
The search for Molly Bish was the most expensive search in Massachusetts state history, Heather Bish said.