LOS ANGELES (AFP) - A male nurse has been arrested in Arizona on suspicion of assaulting an incapacitated woman who gave birth at a long-term care facility, in a case that has shocked the nation.

The 29-year-old victim - who police said "was not in a position to give consent" - gave birth late last month to a baby boy, sparking an investigation.

The woman, who has not been identified by name, had been described as being in a vegetative state, but her family objected to the description.

The suspect - identified as Nathan Sutherland, age 36 - has been charged with one count of sexual assault and one count of vulnerable adult abuse, Phoenix police Sergeant Tommy Thompson told a news conference.

Sutherland's DNA was matched to that of the baby, leading to the arrest, according to police.

The authorities said Sutherland is a licensed practical nurse who was responsible for providing care to the victim at the time the sexual assault took place. He had worked at the privately owned facility - Hacienda HealthCare in Phoenix - for about eight years.

'TROUBLED BEYOND WORDS'

The unidentified victim, a member of the San Carlos Apache Tribe, had been at the facility for roughly a decade. Her caregivers said they were not aware she was pregnant.

"This is a facility that you should be safe in, and someone wasn't," Mayor Thelda Williams told reporters on Wednesday (Jan 23).

The care centre issued a statement saying that Sutherland was fired on news of his arrest.

"Every member of the Hacienda organisation is troubled beyond words to think that a licensed practical nurse could be capable of seriously harming a patient," the statement said.

"Once again, we offer an apology and send our deepest sympathies to the client and her family, to the community and to our agency partners at every level."

Phoenix Police Chief Jeri Williams said she had not encountered a similar case during 30 years in law enforcement.

In a statement issued on Tuesday through their attorney, the victim's family sought to clarify her condition, saying that she was not in a coma but had "significant intellectual disabilities as a result of seizures very early in her childhood".

"She does not speak but has some ability to move her limbs, head and neck," the statement said.

"Their daughter responds to sound and is able to make facial gestures. The important thing is that she is a beloved daughter, albeit with significant intellectual disabilities."

The baby, born on Dec 29, is being cared for by the woman's family and is said to be in good health, Sergeant Thompson said.

"We can't always choose how we come into this life, but what we can choose to do as a community is love this child, and that's what we have the opportunity to do," he said.

Phoenix police were made aware of the pregnancy the day the child was born, when they received an emergency call about a baby in distress.

In light of the woman's condition, they then began to collect DNA samples of male employees at the care facility who had contact with her.

The authorities learnt on Tuesday that Sutherland's DNA matched the baby's, and he was arrested and taken into custody.

The scandal led to the suspension of one of the woman's physicians and the resignation of another.

The chief executive officer of the facility also resigned earlier this month.