Attorney General Henry McMaster said Tuesday another 12 subpoenas could be issued by the end of the day.
Gas prices shot up shortly before Hurricane Ike struck the Texas coastline and its numerous oil refineries. McMaster said more than 3,000 consumers have since complained to local police, the state Consumer Affairs Department and his office.
State law allowed McMaster to criminally investigate the claims after President Bush declared a state of emergency last week. It's unclear when the interviews will begin.
The average price Tuesday for a gallon of regular gas was $4.102 in South Carolina. That's up from $3.531 a month ago and $2.628 a year ago.