As Swedish officials boarded and searched the cargo ship Caffa in the Baltic Sea, they tied the vessel to allegations of sanctions evasion and stolen grain trafficking, according to Swedish officials reported by TT. The investigation was announced Saturday following the boarding in Swedish territorial waters, when authorities also conducted interviews with the crew.

Officials said the Swedish Coast Guard reported that the crew of the Caffa is predominantly Russian and that the ship appears on Ukraine’s sanctions list. Swedish authorities also said the ship was allegedly sailing under a false flag at the time they boarded it, with TT reporting that it had been flying a Guinean flag.

Sweden’s Coast Guard said it boarded the Caffa in Swedish territorial waters to search the vessel and interview those on board, TT reported. Swedish authorities also said they had concerns about the ship’s seaworthiness and that a person is under criminal investigation, although they did not provide additional details about the Caffa or its crew at the time.

The case also fits into Sweden’s broader effort to tighten controls on what authorities describe as Russia’s “shadow fleet” of older, aging ships that can be used to transport oil and gas or carry stolen Ukrainian grain. Last year, Sweden said it would step up insurance checks on foreign ships—not only those calling at Swedish ports but also those passing through Sweden’s territorial waters and exclusive economic zone.

The Coast Guard and the Swedish Maritime Administration were tasked with collecting insurance information as part of that expanded effort. Authorities have said that the average age of vessels associated with this kind of activity is around 18 years, putting them near the end of their life span and potentially more vulnerable to accidents if they are not well maintained.

In this investigation, Swedish officials said they had not yet indicated whether they believe the Caffa is part of the shadow fleet. They also did not specify what evidence, beyond the allegation of stolen grain transport, they were relying on in their criminal investigation.

The Swedish authorities’ next steps were not detailed in the initial briefing, including whether they plan further actions beyond the search and interviews in territorial waters.