Prosecutors said Wednesday they have opened an investigation into a Supreme Court judge who ordered the detention of former chief prosecutor and presidential candidate Thelma Aldana, who gained international renown for pressing high-profile graft cases against Guatemala's wealthy and powerful.

A spokeswoman, Julia Barrera, said the probe of Judge Víctor Manuel Cruz Rivera involves purported acceptance of bribes.

The announcement followed a report from the newspaper El Periodico that Cruz allegedly received millions in return for issuing the detention order for Aldana on March 18. He hasn't commented on that report.

Supreme Court spokesman Mario Siecavizza said the court did not have knowledge of the case.

"Criminal responsibility is personal, and it will be the judge who must resolve his situation," Siecavizza said.

The judge's secretary, Karla Douma, said he could not immediately comment.

Cruz also has received security protection from a government agency that normally provides exclusive protection to the president and his family, including bodyguards and an armored vehicle, El Periodico said. The newspaper said he had been receiving that benefit since a week after ordering Aldana's arrest.

The detention order was never executed as Aldana was in El Salvador at the time. She has not returned to Guatemala.

Aldana and a U.N.-supported anti-corruption commission sought, unsuccessfully, to prosecute current President Jimmy Morales, but lawmakers have not approved measures to withdraw the immunity he enjoys as sitting president. He denies wrongdoing.

Rotman Pérez, Aldana's lawyer, said the investigation of Cruz offers further reason to doubt his impartiality and argued that the judge should be removed from his client's case.

"We hope this is not simply the beginning of an investigation due to social pressure, but rather a diligent investigation and not just a passive attitude," Pérez said.

Cruz has heard other high-profile cases including an investigation of former Judge Blanca Stalling on accusations of influence-trafficking and a recent case involving alleged bribes paid by businesspeople to lawmakers during the administration of ex-President Otto Pérez Molina.

Pérez Molina, who is behind bars on corruption charges, was put there in part by Aldana, whose office was instrumental in bringing the case against the then-president in tandem with a U.N.-sponsored anti-graft commission. He denies the charges.

Two other ex-presidents have also been jailed on corruption allegations.

The 63-year-old Aldana launched a political career after leaving her prosecutor post last year. Around the time she became a presidential candidate, a group of friends and relatives of people Aldana put behind bars filed a complaint against her over a purported hiring irregularity.

The same day her candidacy was formally registered, Cruz issued the detention order for Aldana. She has said she will not return to El Salvador until she feels it is safe.