A week after a jury found an Iowa cancer patient guilty of growing marijuana, his parents are being spared further prosecution.

Dottie Mackenzie, 75, and Chuck Mackenzie, 76, were charged last summer with hosting a drug house, which is a serious misdemeanor, for allowing Benton Mackenzie, 48, to grow marijuana at their Long Grove home.

Scott County District Judge Thomas Reidel acted on a motion by prosecutors and dropped the charge Wednesday.

"I think public pressure had a great deal to do with it, and the fact they had absolutely no evidence," Dottie Mackenzie said when reached at home Thursday.

Benton Mackenzie and his wife, Loretta, 43, were convicted July 9 of felony manufacturing marijuana, conspiracy, violation of the drug tax stamp act and possession of drug paraphernalia.

Their son, Cody, 22, was convicted with misdemeanor possession of marijuana and paraphernalia. They await sentencing.

The Mackenzies say they have received an outpouring of support from across the country and the trial has sparked a media frenzy, including Facebook pages and a petition to President Barack Obama to "pardon the Mackenzie family" posted July 11 to the administration's website.

Dottie and Chuck Mackenzie were supposed to go to trial next week when prosecutors first approached them with a plea deal earlier this week, they said.

"They offered a plea, if we plead guilty to gathering and paraphernalia, and I said absolutely not," Dottie Mackenzie said. "We're not guilty of any of those."

Then prosecutors tried another bargain: Stay out of trouble for six months and charges will be dropped, the Mackenzies said. They refused that, too.

On Tuesday, a Scott County prosecutor filed a motion to dismiss. It stated: "The defendant has no prior criminal history and evidence shows that although they had knowledge of the growing of marijuana on their property they did not actively participate in the growing or use of marijuana."

Scott County Attorney Mike Walton deferred to court filings when asked to comment.

"Detectives were just determined we were criminals, and they painted us as a whole family of criminals," Dottie Mackenzie said.

The parents were at first skeptical of their son's use of marijuana to treat his terminal cancer, especially his father. He retired after 22 years in the U.S. Army as a non-commissioned officer who used to catch soldiers smoking pot and throw them in jail.

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Then they saw how the drug benefited Benton's health, they said.

Benton Mackenzie was diagnosed with angiosarcoma in 2011. He says he grew marijuana in order to treat his cancer with oil derived from the plant. A judge barred him from raising that defense at trial.

Benton's parents took him and his family into their home not long after his diagnosis. They say they were aware he was growing marijuana to make oil.

"Do we help him and break the law, or do we turn our backs?" Dottie Mackenzie asked. "I don't know any parent who would do the latter."

Chuck Mackenzie now has to deal with another matter. Two days before his son's guilty verdict, he got a notice that his right to conceal/carry permit had been revoked in light of the charge that was against him at the time.

He's going to fight that, but he's not yet sure how.

Meanwhile, the couple say they have long wanted to move to Texas, and Iowa's judicial system has pushed them that much closer to their goal.

"We have a legal system," Dottie Mackenzie said. "We don't have a justice system, which is too bad."