Two administrators pleaded guilty Friday to 101 fraud and other charges related to a case that prosecutors say was the largest medical-fraud operation in the nation, while three others charged are expected to go to trial later this year.

According to the report in the Orange County Register, four of the five defendants, office workers at a Buena Park surgical outpatient center, including an attorney, already were tried and convicted in Superior Court Judge Thomas Goethals court in November after a 10-week trial on charges either of filing false tax returns or failing to file taxes or both. A doctor, also charged in the case, has not been tried yet.

The four defendants already prosecuted in the first phase of their cases were personnel connected to Unity Surgical Outpatient Center, where healthy people from all over the United States were recruited for unneeded surgeries, including tummy tucks and hysterectomies, generating $154 million in billings to insurance companies.

When Goethals sentenced the four in December to prison terms on the tax-evasion convictions and ordered them to pay millions in restitution in the first phase of the case, he also told them he would add no additional time to their sentences if they plead guilty to the fraud counts.

The judge said then he felt the tax convictions and the fraud charges were all part of the same “ugly, expensive … felonious scenario.”

Administrators Rosalinda Landon, 66, who received five years and four months on the tax counts, and Dee Francis, 63, who was sentenced to six years in prison on tax charges, accepted the judge’s offer. Unity accountant Andrew Harnen, 58, received the same term as Landon, and lawyer Roy Dickson, 64, got two years and eight months. All four defendants were ordered to pay restitution, ranging from $41,000 to $1.1 million. Harnen and Dickson, each facing more than 100 counts, including insurance fraud and grand theft, did not take the judge’s offer and will to go to trial later this year.

The case is expected to last more than six months, which would make it one of the longest criminal trials in Orange County. If convicted on those counts, the two face more than 55 years in prison.

Orange County prosecutors William Overtoom and George McFetridge have said that Unity doctors performed 1,307 invasive procedures on patients, including some who were recruited and paid between $300 and $1,000 to undergo unnecessary colonoscopies, hysterectomies, the removal of cysts, and treatment of sweaty palms and hemorrhoids.

The prosecutors say Unity billed insurance companies $154 million in a scheme in which 2,841 healthy people from all over the country were recruited for the unneeded surgeries.