An Oregon woman whose prisoner boyfriend died after they shared a meth-laden kiss has been jailed for two years on a drug conspiracy charge.

Melissa Ann Blair and Anthony Powell kissed at the end of her visit to see him last year at the Oregon State Penitentiary. The embrace saw her pass seven tiny balloons filled with methamphetamine into his mouth.

Prosecutors said two of the balloons split in Powell's stomach shortly afterwards, leading to his death from methamphetamine toxicity.

US district Judge Marco Hernandez said Blair was part of a scheme concocted by Powell and others to smuggle drugs inside the prison.

Powell, 41, was serving a life sentence for aggravated murder in the stabbing death of his mother-in-law.

Judge Hernandez said: "It was tragic and sad but he shares responsibility for what happened."

The court also ordered Blair to be supervised for three years after her release and complete a number of drug treatment and mental health programmes. She pleaded guilty to the conspiracy charge.

Blair's lawyer John Ransom said outside court that the 46-year-old felt coerced by Powell, even though he was behind bars. He admitted his client used methamphetamine, but claimed she was not an addict.

"It was a very Svengali-type situation where he had total control over her life," Ransom told the Associated Press. "She had to do whatever he said."

Melissa Ann Blair who went to visit Anthony Powell to smuggle methamphetamine into the jail last year
Melissa Ann Blair who went to visit Anthony Powell to smuggle methamphetamine into the jail last year

Brandy Pokovich, a close friend of Powell's, attended the hearing and said she had become pen pals with the prisoner after he wrote to her husband — a former inmate — but she replied to him instead.

Pokovich said they went on to form a bond through letters, phone calls and visits over the following 12 years.

She referred to herself as Powell's "sister by choice" in a victim impact statement read to the court.

Pokovich added: "Now, because of the choices that were made, I no longer can pick up the phone and hear his voice, I can't go on a visit and see his big cheesy smile and get the best hug in the world."

However, outside the court, Pokovich said she helped Powell find girlfriends by using social media accounts and introduced him to Blair.

Four other defendants in the case have also pleaded guilty to a drug conspiracy charge and will be sentenced over the coming weeks.