Transparency International Ghana Executive Director Mary Addah has urged the Office of the Special Prosecutor (OSP) to conduct an extensive investigation into the Ghanaian dimension of the Asante Kweku Berko bribery case, insisting that all institutions and individuals involved in the deal’s value chain should be examined.

According to her, the investigation should not be limited to the five persons already identified by the OSP as persons of interest, but should extend to every individual and institution that may have handled or interacted with the project.

Speaking on Joy FM’s Top Story on Wednesday, August 26 , Ms Addah said institutions including GRIDCo and others connected to the transaction should be called upon to assist the investigation.

“I think it should be very extensive. Mention institutions, including GRIDCo and others. So everybody in the value chain who may have at one point dealt with this issue has been investigated, or has been called upon to support the process,” she said.

She explained that a comprehensive investigation would help establish whether individuals who were involved in the process played any meaningful role in the alleged scheme.

According to her, expanding the scope of the probe does not mean everyone examined will eventually be implicated.

She stressed that investigations are intended to establish the facts and either confirm, validate or disprove allegations. “Remember, investigations are either to confirm, validate, or otherwise,” Ms Addah said.

She therefore believes the OSP should initially cast its net wide and subsequently exclude individuals who are found not to have played a critical role.

“It doesn't take away from the process if we expand it, and then at a second point decide to be linked and remove those who may not have played a critical role,” she explained.

Ms Addah said a broad investigation would also benefit individuals and institutions that have no involvement in wrongdoing, as it would allow them to be cleared based on evidence rather than assumptions. “It's for their own benefit as well that everybody is looked into,” she added.

Her comments follow the OSP’s identification of former Power Minister Kwabena Donkor and four others as its main persons of interest in the Ghanaian aspect of the bribery case involving Asante Kweku Berko.

The other persons named are Francis Walkson Kwesi Gyata, a former technical adviser to the Minister of Power; Solomon Adjetey Sowah, a former deputy director at the Ministry of Power; Lindin George Nii Mettle, a former director at Tricop Group Limited; and Baffour Ankomah Brobbey, an employee of Tricop Group Limited.

The OSP’s investigation follows Berko’s conviction by a federal jury in Brooklyn, New York, on August 3, 2026, over a bribery scheme involving more than US$1 million.

Berko, a former Managing Director of the Tema Oil Refinery, was convicted over allegations that he conspired to pay bribes to multiple Ghanaian officials between 2014 and 2015 in connection with the development and financing of a 370-megawatt fuel oil plant in Tema.

The project involved the Government of Ghana, Turkish energy company AXA Energy Eratim and Goldman Sachs.

The OSP has said it provided investigative and evidentiary assistance to the US Federal Bureau of Investigation through Ghana’s mutual legal assistance framework, with the US Department of Justice acknowledging the assistance.