The woman gave birth to a boy Dec. 29. Staff members told a 911 operator that they had not known she was pregnant.
"From the minute we first became aware of the crime, we have virtually worked non stop seven days a week to resolve this case," Phoenix Police Chief Jeri Williams said in announcing the arrest Wednesday morning.
Williams joined Mayor Thelda Williams at Phoenix police headquarters to provide an "important" update on the investigation into the rape.
Sutherland is a licensed practical nurse who was primarily responsible for caring for the victim at the time of the assault, according to police. He's worked at Hacienda since 2011.
State records show he was first licensed as a clinical nursing assistant in 2005, before he became an LPN.
The Phoenix police crime lab on Tuesday determined a DNA sample taken from Sutherland matched the baby. He was taken into custody the same day.
Police announced they would be testing the DNA of all employees during a Jan. 8 media briefing.
Phoenix police Sgt. Tommy Thompson said police didn't have the opportunity to collect Sutherland's DNA through a court order until Tuesday.
Sutherland declined to answer investigators' questions after he was taken into custody Tuesday, according to Thompson.
Sutherland was booked into Maricopa County Jail Wednesday, charged with one count of sexual assault and one count of vulnerable adult abuse. Maricopa County Superior Court records show Sutherland has not been charged with any other major crimes.
Thompson said they are still working to determine whether Sutherland assaulted other victims inside the 60-bed facility.
Thompson said the baby was full-term and has since been released from the hospital.
"We can't always choose how we come into this life, but we can choose as a community how we will love this child - and that's what we need to do," he said.
According to court records, the woman, who is a member of the San Carlos Apache Tribe, has been a patient at Hacienda for 26 years. The records say the woman is "not alert" and needs a "maximum level of care."
In the weeks since the 911 call calling for help after the child's birth, police and state agencies have launched investigations and the director of the facility resigned. Investigators obtained DNA from male workers at the facility.
Hacienda HealthCare also hired former Maricopa County Attorney Rick Romley to conduct an independent investigation into patient safety.
