"At present there is one suspect," Strelcenoks said.
Strelcenoks did not reveal the precise reason for Magonis' detention, simply repeating that it is related with large procurements that media have reported about already.
He also explained that no information had been released about Magonis' detention because several searches followed.
"Officers were working intensely, about ten searches were conducted," Strelcenoks said, adding that there was cooperation with the Estonian authorities.
The KNAB head also said that information published by the media that Magonis had tried to escape detention was false but he did confirm that the sum found in Magonis' car was about half a million euros.
The Latvian Corruption Prevention and Combating Bureau (KNAB) has launched a criminal investigation against Ugis Magonis for accepting a large bribe.
Magonis was swiftly sacked from his job as head of Latvian Railways after he was suspected of accepting a bribe worth nearly 500,000 euros in connection with a tender for four diesel locomotives organized by the railway company's subsidiary, LDZ Ritosa Sastava Serviss, which was won by Estonian businessman Oleg Ossinovski's company Skinest.
Latvijas Dzelzcels is a state-owned company, involved in freight transportation by rail and the maintenance of infrastructure.