Jurors in Delaware are expected to hear closing arguments Wednesday after 60-year-old Melvin Morse finishes testifying in his trial on endangerment and assault charges.
Morse could face more than 20 years in prison if convicted on all charges.
Morse says the alleged waterboarding was his attempt to help the girl wash her hair.
The girl, now 12, and her mother have testified that Morse used hair-washing as a threat or punishment.
Morse, who has researched near-death experiences involving children, denies police claims that he may have been using waterboarding to experiment on her.
The allegations came to light after a neighbor reported to police that Morse had dragged the girl on a driveway.
