A career criminal arrested in Montgomery County for marijuana possession in April 2011 has been sentenced to 37 years in prison after, prosecutors said, he launched an intimidation campaign against a state witness.

Michael Eugene Donati left marijuana plants on the witness's porch and bags of pot in his shoes, sent threatening emails to the witness's workplace and emailed false tips to various police agencies implying that the witness was growing marijuana, prosecutors said.

Donati, of Rockville, was arrested in April 2011, after, police said, he attempted to sell marijuana at Growlers Brewery and Restaurant in Gaithersburg. Shortly after his release from custody on bond, prosecutors said, he began harassing a bouncer and the owner of the restaurant, both witnesses in his possession with intent to distribute trial.

Donati has been convicted in numerous sexual assault cases ranging from indecent exposure to two rapes: the 1980 knife-point rape of a 23-year-old Fairfax woman and the 1982 rape of a Montana woman. He was last released from prison in 2004.

After his arrest in April, Donati began sending threatening, anonymous emails to Growlers that included homophobic and ethnic slurs, prosecutors said. Later, he began sending anonymous tips to the Montgomery County police and the U.S. Park Police, alleging that a bouncer at Growlers who had witnessed his arrest, Jason Allen, was growing pot in public parks in the county, according to court documents. He planted marijuana plants on Allen's porch and left bags of marijuana in a pair of shoes sitting on the porch, then called police to report that Allen was growing marijuana in his house, police said. Posing as a tipster, he told police he would reveal the location of Allen's "grow site" if police gave him $50,000 or dropped charges against him, according to court documents.

Eventually, police obtained a search warrant for Donati's house and evidence linking him to the emails sent to police agencies, as well as a homemade "how to grow marijuana" video, according to court documents. Police said the email campaign ended immediately after they executed the search warrant.

Donati was found guilty in March and sentenced to 37 years in prison on Friday on one count of distributing marijuana, two counts of obstruction of justice, 15 counts of misuse of emails, two counts of false statements to police and two counts of intimidating witnesses. He will not be required to serve probation when he is released, however.