The woman had been a patient at the Phoenix facility for more than a decade after nearly drowning, according to azfamily.com, which broke the story; police declined to provide NPR with details about their investigation.
"We're not going to point out who we've obtained DNA from or who we intend to get DNA from", he said.
The reported birth - and the sexual assault on a vulnerable individual that must have preceded it - has cast a harsh glare on conditions at a nonprofit organization that bills itself as a leading provider of health care for Phoenix's medically fragile.
Hacienda HealthCare says investigators served a warrant Tuesday, asking for DNA samples from male employees.
Hacienda chief executive Bill Timmons has also resigned amid the scandal.
A Hacienda HealthCare facility in Phoenix, Arizona.
According to its website, Hacienda HealthCare serves more than 2,500 people throughout Arizona each year.
The mother has been living at Hacienda after suffering from a near-drowning incident left her brain damaged over 14 years ago.
RAPE PROBE: Hacienda HealthCare has said it is cooperating with police (Pic: ABC 15) "Sadly, one of her caretakers was not to be trusted and took advantage of her".
"Hacienda stands committed to doing everything in our power to bring this police investigation to a quick conclusion".
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Gary Orman, the executive vice president of the company's board, said it would "accept nothing less than a full accounting of this absolutely horrifying situation".
Police in Phoenix are investigating reports of sexual assault, they confirmed.
A male patient also complained several staff members walked in on him while he was naked and showering with the assistance of a female member of staff in December 2017, according to records from the Department of Health and Human Services.
"From what I've been told, she was moaning", a source told Phoenix CBS affiliate KPHO.
A spokesman for Arizona Gov. Doug Ducey (R) called the recent report "deeply troubling" in a statement to The Washington Post.
The department of health ordered Hacienda to implement "heightened safety measures", spokeswoman Melissa Blasius-Nuanez said.
"I saw people disappear and never come back", she said.
The staffer, along with the director of the facility, said those incidents occurred because they needed to access the trash cans or supplies stored in the shower room.
A former caregiver of the victim whose identity was kept private expressed shock to ABC 15 that the facility's staff did not realize the patient was pregnant.