A former environmental minister once again declared his innocence after another preliminary hearing began Thursday in the controversial and complex Infinito Gold criminal case.

The former minister is Roberto Dobles-Mora.

Also an accused in former president Óscar Arias-Sánchez. The case involves official actions in favor of the Canadian firm Infinito Gold Ltd. Arias, in his capacity as president signed a decree in 2008 that said the Las Crucitas* open-pit mining project in Cutris, San Carlos, was in the national interest.  Dobles is involved because he, too, signed off on the measure.

The case is being hear in the courts in Goicoechea*. Presiding Judge Karla Bonilla Ballestero will decided if the case will go to a full trial. The allegation is that the presidential decree was based on false facts.

The open pit mine had been praised by officials as a major economic development in northern Costa Rica. Environmentalists and activists condemned the project for being a potential source of pollution. Hundreds of students rallied for months against the project. One activist even walked from San Jose to the site to attract media attention.

Officials of the Canadian firm estimated that there were billions of dollars of gold in the ground that could be extracted by a leaching method.  The decree by Arias provided certain bureaucratic benefits to the firm to expedite development of the project.

The case has been in and out of the courts and appeals panels for nearly nine years.

"I am totally innocent, what is being accused. When I signed the documents that I had to sign, I did not knew that there was an illegality and of course the ministers sign many things And this project had been studied for 17 years, which is why I have indicated that today I am innocent," Dobles said on leaving the hearing. Testimony is expected to last through the first week of next month.

In addition to Arias and Dobles, there are six more defendants who were employees of the National Environmental Technical Secretariat and the National Registry.

According to the allegation of the prosecution, the defendants committed irregularities in issuing the decree of national convenience in 2008.

In 2010 the Contentious Court annulled the decree, which allowed an accusations to be opened against the suspects.

In January 2015 Dobles was judged and found guilty in January 2015. The former minister was sentenced to three years in prison for the fault of malfeasance. However in November of that year an appeals panel annulled the sentence.

The Public Prosecutor's Office requested the dismissal of the case against Arias in 2014, and a criminal court accepted the request. For that reason, there was never a trial.