A court ruled to keep three people under arrest in an alleged €800,000 bribery case for tenders over delivering more than 200 buses and trolleys to Rīga.
The other two people the court arrested are Aleksandrs Krjačeks and one Edgars Teterovskis.
No official comment has yet been offered over their role in the case.
Krjačeks, a member of the Honor to Serve Rīga party, is the head of the Alkom Trans company and one of the largest donors to the Harmony party ruling in Rīga. This year, he donated €3,000 to the party.
The Alkom Trans website says it was established in 1992 and specializes in international transit.
It is a partner of Škoda and actively participated in introducing the Škoda 15T low-deck trams in Latvia. Company personnel provide the maintenance of the Czech trams.
According to the LETA news agency, in 2016 Škoda Transportation signed an agreement with Rīgas Satiksme on supply of 20 low-deck trams for €62.59 million. The company also supplied trams for €52 million to the company in 2008.
On December 11 and 12 news broke out over the arrest of eight people in Latvia and Poland over alleged graft in the Rīgas satiksme municipal transport company.
High-profile businessman Māris Martinsons is among the people arrested by the KNAB, as well as Igors Volkinšteins (the court has remanded the two in custody), the director of the Department for Infrastructure Maintenance and Development at the Rīga City Council.
Rīga mayor Nils Ušakovs (Harmony) has suspended the head of Rīgas satiksme for the duration of the investigation.