“We don’t know what diagnosis supported those tests,” Mr. Pattis wrote in an email on Tuesday to The New York Times. “Was she critically ill? Did she plan a final farewell intended to assure Fotis never saw the kids? We are looking for Jennifer and for answers.”

The husband, Fotis Dulos, 51, along with his girlfriend, Michelle Troconis, have pleaded not guilty to hindering the prosecution and tampering with evidence.

In an interview with NBC 4 broadcast on Tuesday night, Mr. Dulos declined to comment on the specifics of the case but said, “I never wanted Jennifer out of the way.”

Ms. Dulos and her husband had been going through a tempestuous divorce, accumulating an enormous volume of court motions regarding disputes about bed times, doctors for the children and steep lawyer fees, among many other things. Mr. Dulos claimed in a court filing that the children were being kept under armed guard at their grandmother’s apartment in New York City.

“We are exploring all possibilities, including that she made good on a threat she made to him prior to her disappearance: ‘I’ll do anything I have to do to make sure you never see the kids again,’” Mr. Pattis said. “This, together with evidence of an alarming number of medical tests she endured just prior to her disappearance, makes the revenge-suicide hypothesis something we are taking very seriously as we continue our investigation.”