As a Senator he had to answer to accusations of working with the fugitive Roberto Soto Prieto who had allegedly stolen US$13.5 million and with whom Laserna had connections in Austria through his work as Ambassador, at which time Soto Prieto was an alleged refugee in that country, and through alleged business deals in which Soto was found to be indirectly involved. At the request of the Colombian Minister of Foreign Affairs Noemí Sanín the last five ambassadors to Austria and all employees of the embassy were investigated by the Inspector General of Colombia and the Attorney General of Colombia, among those was Mario Laserna Pinzón. Laserna was later cleared of all charges in respect to the case.