The four men are being retried after the Supreme Court quashed a verdict sentencing Sobol to one year and 11 months' imprisonment. Sobol is the husband of Godrana Sobol, an MP of the ruling coalition's Social Democratic Party.
The other defendants are Davor Mihelcic, a physician from Rijeka sentenced to two years' imprisonment, and former senior Interior Ministry officials Rino Aralica and Miroslav Crnic, each given six-month suspended sentences.
About 20 witnesses will be heard at the Zagreb County Court retrial.
Sobol was charged, as an assistant interior minister in charge of financial affairs, with abuse of office at Mihelcic's incitement by enabling him to sign an unlawful contract with the ministry for specialist examinations for police officers in his Delnice surgery, which was not licensed to perform occupational medicine examinations.
Mihelcic signed a three-year contract with the Interior Ministry, in effect from 2001 through 2003, charging HRK 424,000 kuna for examinations that were never performed. After paying taxes, he earned a net profit of HRK 360,000.
Sobol and Mihelcic were also found guilty of a 2003 contract for examinations of intervention police officers who provided security for Pope John Paul II during his visit to Rijeka in 2003, which Mihelcic charged HRK 108,000 kuna, making a net profit of HRK 92,000.
Under the verdict, the doctor had to pay back HRK 468,000.
Aralica and Crnic were convicted of verifying a bill of HRK 18,000 which Mihelcic charged for the examination of six special police officers.
The Supreme Court quashed the conviction of Vladimir Pavlekovic due to errors of fact, granting the appeals of the four defendants and ordering a retrial before a new panel of judges chaired by Ivan Turudic.
The trial resumes on June 12.