Shot on Christmas

In a Scottish castle bought by a Russian oligarch, a beautiful model was murdered on Christmas night. The police immediately arrested her boyfriend, as all the evidence pointed to him: the guy had argued with the deceased and his fingerprints were found on the gun. At the same time, each of the guests had a solid alibi. However, the suspect stubbornly denied his guilt. He did not convince the police, but he managed to convince Drongo. The expert analyst decided to thoroughly investigate the family relationships of the oligarch...