He acknowledged that Jayme may not be the same person she was before she disappeared.
"He concealed his identity and concealed her from other people also", Fitzgerald said.
"I was terrified, but I didn't want to show her that", Nutter told the AP.
She was believed to have witnessed the murders of her parents but was not considered a suspect based on evidence recovered at the scene, police said at the time.
The Minneapolis Star Tribune quoted a teacher at a local school as saying a neighbour walking her dog had knocked on her door after having found Jayme.
"Praise the Lord", Ms Allard said between sobs.
Sue Allard said she "just had this feeling" about today and said she "can't wait to give her a hug". The two went to the home of Peter and Kristin Kasinskas, who said Jayme was skinny and dirty, wearing shoes too big for her feet, but appeared outwardly OK.
Jayme's cousin, Seara Closs, shared her relief on social media. "From the bottom of my heart THANK YOU!" he wrote in the news release on Thursday.
He described her escape from her captor as "unthinkable", adding: "That is the will of a kid to survive". The sheriff also said investigators don't believe Patterson had any contact with the family.
A press conference will be held Friday at 10 a.m.
Fitzgerald said investigators believe the girl was "the only target" but they weren't yet able to say how they believe the suspect learned about her.
Despite arriving just minutes after the call, deputies found her parents shot dead and Jayme missing.
October 29, 2018 - Prosecutors announce they have charged a man with burglarizing the Closs home but say he's not a suspect in the case. The log does not indicate who made the 911 call, but the dispatcher heard yelling in the background. He said a search warrant is now being served on the Gordon home and authorities are also investigating several cars that belong to Patterson, who he said has "zero" criminal history.
Authorities spent months searching for her and received thousands of tips, to no avail until Thursday. The FBI offered a $25,000 reward for relevant information.
October 23, 2018 - About 2,000 volunteers from as far as Minneapolis help with another ground search.
As Douglas County Sheriff ChrisFitzgerald explained it, a woman named Jeanne Nutter was walking her dog in a town about an hour away from Barron on Thursday afternoon, when she was approached by a girl claiming to be Jayme.