GUATEMALA CITY (AP) — A Guatemalan judge has ruled that an investigation will proceed against ex-President Alvaro Colom in a case of alleged corruption involving bus concessions during his 2008-2012 administration.

Judge Eduardo Cojulum ruled Thursday that Colom should be investigated for possible crimes of embezzlement and fraud along with 12 of his former Cabinet ministers, including the current president of Oxfam International.

Colom and the ministers were arrested Feb. 13. He told the judge he is innocent and his project to upgrade public transport aimed to prevent deadly attacks on bus drivers and passengers.

The case centers on 25-year concessions for Guatemala City bus routes that were auctioned off during Colom's presidency. Prosecutors say the process was deeply flawed and it is suspected that the government was defrauded out of millions of dollars.