(GREEN LAKE, Wis.) -- A husband and father of three who vanished at a Wisconsin lake this summer may have faked his own death and fled to Eastern Europe, authorities said, and the sheriff is now urging the missing man to come forward.
"Our most important thing, for us, is to know that you're safe," Green Lake County Sheriff Mark Podoll said in his message to Ryan Borgwardt. "We can talk through all this and we can work things out."
The case began on the morning of Aug. 12, when authorities learned Borgwardt, 45, hadn't returned home and was last known to be on Green Lake, according to the Green Lake County Sheriff's Office.
Borgwardt last texted his wife on the night of Aug. 11, saying he was turning his kayak around and heading to shore soon, Podoll said.
Officials discovered Borgwardt's overturned kayak and life jacket in the lake, authorities said, and they later found his fishing rod and tackle box.
Responders believed the missing dad drowned and they scoured the lake using divers, drones, sonar and cadaver K-9s, officials said.
"The search continued for about 54 days, with no sign of Ryan," the sheriff said during a news conference on Friday. "Near daily drone searches were completed. And Bruce's Legacy [a volunteer search organization] methodically searched approximately 1,500 acres. ... Keith Cormican, [who leads] Bruce's Legacy, sifted through hours and hours of sonar data and images."
"Keith's expertise and equipment led us to believe either something very odd occurred and Ryan was outside the area that had been searched, or something else had occurred," the sheriff said.
The case took a turn in October when investigators discovered Borgwardt's name had been checked by law enforcement in Canada on Aug. 13, the sheriff said.
Authorities also learned Borgwardt had been communicating with a woman from Uzbekistan, the sheriff said.
Other behavior included clearing his browsers the day he disappeared, inquiries about moving funds to foreign banks, getting a new life insurance policy, obtaining a new passport and replacing his laptop hard drive, the sheriff said.
"I was totally shocked," Podoll told ABC News on Monday. "It was just unbelievable that we would have a case like this where some party actually staged his death."
Authorities have stopped searching the lake.
"As far as we know, he's someplace in Eastern Europe," the sheriff told ABC News.
Investigators are "looking into what charges could be filed," Podoll said, adding, "that's a work in progress."
Authorities hope to pursue restitution for the expenses of the search, the sheriff's office said.
"He wasted a lot of my time and it cost me a lot of money," Cormican of Bruce's Legacy said.
Podoll said it's not clear if Borgwardt was given help, and he urged anyone with information to come forward.
Podoll praised Borgwardt's wife, whom he said was not involved, calling her "a very, very strong lady."
"I was there when the sheriff broke the news to the whole family. And it was pretty, pretty heart-wrenching to see," Cormican told ABC News. "I feel horrible for the family. They're the ones that are going to really struggle."
ABC News' Karolina Rivas contributed to this report.