Notably, the jury did not convict him on charges related to the fire, even though prosecutors had argued that he was directly involved. Had it not been for a relatively new technique that used tree DNA as evidence, Mr. Wilke might not have been convicted on the other charges.
Prosecutors said this was the first time that such evidence had been used in a federal criminal trial, although it has been used in state cases and in federal cases that did not reach trial. Researchers hope this will deter future poaching, particularly of bigleaf maples, for which there is now a large database.
Two members of the poaching group testified that Mr. Wilke was standing next to the nest when it ignited and appeared to have set the fire, prosecutors said.
“However, because the fire was set at night, they were not able to see his exact actions, and testified that they did not know exactly how the fire started,” according to the statement. “The jury did not convict Wilke of the two federal counts related to the forest fire: setting timber afire and using fire in furtherance of a felony.
A lawyer for Mr. Wilke said in a statement on Tuesday that his client has always maintained that he did not cause the fire and that the jury’s acquittals on those charges reflect that.
“As the sentencing papers reflect, Mr. Wilke has worked hard over the last three years to create a future for himself,” Gregory Murphy, a federal public defender, said in an email. “He looks forward to putting this prosecution behind him.”
A member of the logging crew, Shawn Williams, was sentenced in September 2020 to 30 months after pleading guilty to theft of public property and setting timber afire, Seth Wilkinson, an assistant U.S. attorney, said in an email.
Prosecutors had recommended a three-year sentence for Mr. Wilke, calling him the group’s ringleader, but a judge at sentencing said he had made “positive strides while on pretrial release, and that prison time is more difficult during the Covid pandemic,” according to the statement.
Mr. Wilke was also ordered to forfeit proceeds from the tree poaching and will be required to pay restitution to the U.S. Forest Service in an amount that will be determined at a later hearing, according to the statement.
A government research geneticist testified at trial that the wood Mr. Wilke sold to a mill was a genetic match to three poached maple trees that investigators found in the Elk Lake area.
Like all living organisms, trees have DNA, the research geneticist who testified, Dr. Richard Cronn of the U.S. Forest Service, said in a phone interview on Tuesday night.
“They receive one set of chromosomes from their mom and their dad,” Dr. Cronn said. “That makes it possible to uniquely distinguish every tree out there if we have the appropriate genetic markers.”
In this case, researchers built a DNA database specifically for the Olympic National Forest, sampling 230 trees and coming up with an estimate that the probability of a coincidental match was one in one undecillion — or one followed by 36 zeros, Dr. Cronn said.
One limitation to a more widespread use of this technique in criminal prosecutions, Dr. Cronn said, is that databases must be created for individual tree species. This can be costly and time-consuming, he said, but he added that advances in genomics technology have made doing so easier.
“If you think about a human forensic database, you’re only making it for one species,” he said. “The trees that are targeted for timber theft across the U.S. are really different. We have maple in the Pacific Northwest, walnut in the eastern U.S. We would need a database for each of the species, so that is a bit of a barrier.”
Dr. Cronn said the use of tree DNA in this case would be a deterrent to similar theft.
He said researchers had created a bigleaf maple database of more than 1,100 tree samples, covering a region “basically from the U.S.-Mexico border all the way up to Vancouver Island and Canada.”
“Any time trees are taken in that range can now be investigated,” Dr. Cronn said. “We will be ready at the next trial.”