Yamhill County Jail records show Wolfe, 52, is charged with two counts of aggravated murder and two counts of first-degree kidnapping. He is being held without bond.
KGW-TV reported that authorities were led Saturday to a densely wooded area about 10 miles west of Yamhill, where two bodies were located after about two hours of searching. The Oregon State Medical Examiner's Office on Sunday identified the remains as those of Karissa Fretwell and her son.
Karissa Fretwell had been shot once in the head, the news station reported. Billy Fretwell's cause of death is still under investigation.
Yamhill County District Attorney Brad Berry said before the bodies were found that his office had a strong case against Wolfe for murder. Wolfe was indicted last week by a grand jury.
"There is a lot of other evidence that leads to the conclusion that they have been murdered," Berry said, according to KGW-TV. "At some point, you have so much evidence you can't explain it away as happenstance."
Upkes said on May 24 that despite the charges filed against Wolfe, authorities still held out hope they would find Karissa and Billy Fretwell alive.
"When doing investigations as serious as this, we work toward the worst possible scenario and continue to hope for the best," Upkes said. "Everyone who's been involved in this case continues to hope for the safe return of Karissa and William."
Upkes declined to speculate on Wolfe’s motive for the alleged crimes.
Watch the news conference announcing Wolfe’s arrest, courtesy of KOIN 6 News.
Court records show that Wolfe was ordered in April to begin paying about $900 a month in child support to Karissa Fretwell. The documents also show that Billy Fretwell’s babysitter told investigators his mother confided to her over several months that Wolfe and his wife had threatened to seek custody of the boy.
Bethany Brown, a friend of Karissa Fretwell's, told KOIN 6 News that Fretwell met Wolfe, a security guard, through her work at Jimmy John's. She would deliver sandwiches to Wolfe, who asked her out, Brown said.
Wolfe admitted to investigators he had a sexual relationship with Karissa Fretwell about four years ago, Fox12 in Beaverton reported.
Brown said the young mother sought regular child support for her son about a month before the pair vanished.
"I don't want to think (Wolfe) did anything, but it's just super weird that it was the same time frame," Brown said. "It was, like, three to four weeks ago, and I think her first child support check, she was supposed to receive June 2019, next month."
Read the probable cause affidavit for Wolfe’s arrest below.
Wolfe told detectives he had no contact with Karissa Fretwell or their son following their April 15 court hearing, which he said “did not go well,” and that he had not been to Salem in more than a year, the affidavit says. Cellphone records show, however, that Karissa Fretwell’s phone sent a text message around 2:27 p.m. May 14 using the same cell tower that serves Wolfe’s rural home near Gaston, about 40 miles north of Salem.
KOIN 6 News reported that searchers spent days searching Wolfe's property, as well as an area of Hopewell. Dive teams were also used to search a reservoir in Yamhill County for signs of Karissa Fretwell or her son.
Investigators also obtained data that placed Karissa Fretwell’s cellphone near Cascade Steel in McMinnville, where Wolfe told police he was working his regular 6:30 p.m. to 6:30 a.m. shift the night Fretwell and her son were last seen alive.
The affidavit indicates Cascade Steel surveillance footage from May 13 shows Wolfe leaving the part of the steel mill where he works around 8:45 p.m. on a golf cart. The footage shows him walking through a line of trees and bushes behind the business’ carpenter shop and toward the parking lot.
“Detective Gamble was told by security at the location this would be outside of protocol,” the affidavit states.
The affidavit says cellphone records show Wolfe’s cellphone traveling south, away from the business, around 8:55 that night. At about 9 p.m., the phone was shown to be using the same downtown Salem cell tower that serves Karissa Fretwell’s apartment.
Wolfe’s cellphone remained in Salem for nearly five hours before the data showed him moving north toward his workplace, the affidavit states.
He is next seen on the Cascade Steel surveillance footage walking back through the tree line around 2:35 a.m., according to the document. As he drove the golf cart back toward his area of work, he carried a white trash bag containing unknown items.
“At approximately 2:52 a.m. on May 14, 2019, Michael can be seen leaving the main building from a different door wearing his work shirt,” the affidavit says. “He does not have his backpack and he is again carrying the white trash bag.
“This would not be consistent with Michael’s above described statement he was at work his whole shift.”
Wolfe told investigators he worked at the steel mill until about 6 a.m., but cellphone records showed his cellphone using a tower near his home shortly after 4:30 a.m., the affidavit says. The data indicated that Wolfe’s and Fretwell’s cellphones were in the same areas overnight on May 13 and early May 14.
“Based on the above described facts, the circumstances of Karissa and William’s disappearance and the fact she has not been heard from or seen since the time the described facts indicate Michael and Karissa were together, I believe there is probable cause to arrest Michael Wolfe for the listed crimes,” a detective wrote.
Megan Harper, another friend of Karissa Fretwell's, told KGW-TV she immediately thought of Wolfe when she learned her friend was missing.
"I know that he's previously sent her threatening messages and I know a lot about the custody situation because Karissa vents to me and asks for advice," Harper told the news station.
Besides working at Jimmy John's, Karissa Fretwell was also a student at West Oregon University. The university's president, Rex Fuller, issued a statement late Sunday night in which he said he was devastated to learn she and her son were found slain.
"I know I wasn't alone in wishing for a joyful outcome for Karissa, Billy and their loved ones," Fuller wrote. "My thoughts are with all who knew and cared for them. I know our community will come together and support each other in this difficult time."
An apparent friend, Katy Brockway, wrote on Facebook that Karissa Fretwell was a hardworking and inspirational young woman.
"She always talked about wanting to become a teacher to be able to work with children and to be able to provide a better life for her and Billy," Brockway wrote. "Karissa was kind, intelligent, caring and one of the smartest people I've ever met at WOU. This was a careless, selfish and horrendous act; but that is not how she will be remembered.
“Karissa Fretwell will be remembered for her unconditional love, her fierce friendship and her admirable dedication to be the best mother she possibly could be for Billy.”