A woman testified Thursday that she didn't believe her longtime companion, who was a pediatrician, was washing her daughter's hair when she saw him hold the girl's head under a kitchen sink faucet.

The girl has accused 60-year-old Melvin Morse of waterboarding her. He is on trial in Delaware on endangerment and assault charges.

Pauline Morse said on the stand Thursday that she walked into the kitchen one time and surprised Melvin Morse while he had the now 12-year-old girl's head under the faucet. She said Morse jumped and quickly released the girl, who was coughing and shaking.

Pauline Morse, 41, also told jurors that she didn't believe he was washing the girl's hair.

"He called it washing her hair, but I knew it wasn't washing her hair because there was no soap or anything," Pauline Morse said. She pleaded guilty last year to misdemeanor child endangerment charges and agreed to testify against Melvin Morse.

Melvin Morse has authored several books and articles on paranormal science and near-death experiences involving children. He has appeared on shows such as "Larry King Live" and the "The Oprah Winfrey Show" to discuss his research, which also has been featured on an episode of "Unsolved Mysteries" and in an article in "Rolling Stone" magazine.

Morse, whose license to practice medicine was suspended after he was charged, has specifically denied police claims that he may have been experimenting on the girl. Waterboarding simulates drowning and has been used in the past by U.S. interrogators on terror suspects. Many critics call it torture.

Pauline Morse also testified that Melvin Morse used "hair washing" as a threat or punishment for the girl.

"He would just say 'I'm going to wash your hair,' and he would say 'I will do it again.'"

Pauline Morse pleaded guilty last year to misdemeanor child endangerment charges and agreed to testify against Melvin Morse. Despite witnessing what happened in the kitchen at least once, as well as various other forms of punishment, including making the girl stand for long periods of time, Pauline Morse said she often did nothing to stop it.

"A lot of times I would just go up in my room and ignore the whole thing," she said, adding that she was afraid of "undermining" Melvin Morse.

While recounting how she sometimes heard bumping and crying in the mornings which she thought was from Melvin Morse dragging the girl down the stairs, Pauline said she stayed in bed.

"I didn't want to see," she explained.

The allegations of waterboarding surfaced after Morse was accused of grabbing the girl by the ankle in July 2012 and, as her younger sister watched, dragging her across a gravel driveway. He was arrested and released on bail.

When investigators questioned the girl, then 11, she told them about what she called waterboarding, which she said had gone on for years.

If convicted on each of four felony counts of reckless endangering, Morse could face up to 20 years in prison, but the presumptive sentence for each count is up to 15 months in prison. He faces up to a year in prison for each of five misdemeanor counts of endangering the welfare of a child, and up to a year on one misdemeanor assault charge.

Pauline Morse testified that Melvin Morse had violated a no-contact after his arrest by making calendar entries with messages on his cellphone, which was synched to hers because they shared the same account.

One message presented by prosecutors reads: "I have repented and I am suffering my own created hell."

Defense attorneys were to begin their cross-examination of Pauline Morse later Thursday.

She said her motivations for testifying against Melvin Morse included hoping to be reunited with the girl and her younger sister, who are now in foster care, and because she wanted him "out of our life."