Kansas City, Mo. ? A pharmacist accused of watering down chemotherapy drugs pleaded guilty Tuesday and could get up to 30 years in prison in a case that shocked cancer patients and their families.

Robert R. Courtney, shackled at the hands and ankles, admitted that he committed 158 dilutions of drugs for 34 patients and said he had “no rational explanation” for what he did.

“I have had a long period of time in isolation to reflect on my conduct,” said Courtney, 49. “I am guilty, and I accept full responsibility. To the victims, I am extremely sorry.”

Prosecutors have said he made hundreds of dollars extra per dose.

Authorities have not said whether any patients died as a result of his diluting their chemotherapy drugs. Legal experts have said prosecutors would have faced a daunting task in trying to prove that a cancer patient would have lived if the medication had not been tampered with.

Courtney pleaded guilty to all 20 federal counts against him of adulterating, tampering with and mislabeling the chemotherapy drugs Taxol and Gemzar. Prosecutors will recommend a sentence of between 17 1/2 and 30 years behind bars. No sentencing date was set.

If he had gone to trial and been convicted on all counts, he could have been sentenced to 196 years.

Courtney also faces up to $15 million in fines. And his estimated assets of more than $10 million will be used as restitution for victims.

The pharmacist, who has been jailed since August, has said he began diluting medications to help pay more than $600,000 in taxes and fulfill a $1 million pledge to his church.

Spectators in the packed courtroom included Courtney’s wife, as well as relatives of cancer patients who believe they received diluted doses from Courtney’s Research Medical Tower Pharmacy.

Barbara Wibbenmeyer, a 47-year-old cancer patient from Kansas City who has sued Courtney, called the plea agreement “probably the best thing we can do for the victims at this point. It starts putting closure to the ‘wheres’ and the ‘whens.”‘

“If they do give him 30 years, I’d like to see my mug shot on his wall for the rest of his life,” she said. “I think he needs to see me.”

Courtney has been stripped of his pharmacy licenses and forced to sell two pharmacies. He also faces about 300 lawsuits accusing him of fraud and wrongful death.