"Concluding the investigation" sounds to me like they expect to find her...
Then again, they also said that in Debbie N's case and we have nothing there...
What if the outcome of the polygraphs (him walking out/refusing all 3) IS what led to the search of the house/shed? But without having actual results from questions. The two could still be the same. They could use the polygraph "results" and he could have still refused them. The refusal could have been the result that convinced them that is where they needed to focus.
I do believe they could work around most meds. I also believe most meds that would affect the results would actually cause him to PASS when he shouldn't. Most meds that would affect the results would do so because they calm you.
Innocent people failing polygraphs...
Bill Wegerle failed 2 polygraphs in the murder of his wife in 1986. In 2004 BTK sent a letter containing her license and photos of her body. DNA evidence later proved BTK, (Dennie Rader) killed his wife.
After he failed the polygraph, detectives were able to get Frank Sterling, to confess to the murder of 74-year-old Viola Manville in 1988 and he was convicted. Mark Christie, who passed the polygraph, went on to abduct and murder four-year-old Kali Ann Poulton. Christie was convicted of her murder and recently confessed to Manvilles murder. Frank Sterling was released from prison.
There has been multiple cases where the killer did pass, was cleared as a suspect and sometimes went on to kill many more times.
The Green River Killer (44 more victims)
Charles Cullen (39 more victims)
Lee Anthony Evans (5 victims, case cold for 32 years)