A onetime attorney in Montgomery County was sentenced to 12 years in prison Monday for what prosecutors described as a scheme to steal $1.8 million from an elderly client.

Jonathan Robbins, 59, also used his position as the client’s accountant to take the money, according to prosecutors. The victim, Helen Nutt, was 91 and suffering from declining mental abilities when she died before Robbins’s criminal trial, prosecutors said.

“The defendant chose over and over again to betray the trust of his client, someone he knew was vulnerable,” Montgomery State’s Attorney John McCarthy said Monday.