Finland's National Bureau of Investigation (NBI) on Sunday continued its probe into suspected deliberate damage to subsea electricity and telecom cables in the Gulf of Finland that occurred on Christmas Day.
Investigators suspect that the oil tanker, Eagle S, was behind the damage, with Finnish authorities continuing their investigation aboard the ship on Sunday.
Authorities have conducted a subsea investigation, and found a long trail carved into the seabed according to the investigation's leader, Sami Paila.
"The trail ended where the vessel pulled up its anchor. And from that point an eastward trail continues for several dozen kilometres, and could even be closer to a hundred kilometres," Paila told Yle.
Investigators have added a third criminal heading to the probe: gross interference with telecommunications. Before that, the preliminary probe had focused on gross sabotage while Finnish Customs opened a preliminary investigation of suspected gross regulatory violations.
On Sunday evening, Paila said investigators had made initial findings about the course of events that led to the cable damage.
Repair ship heading to site
A cable repair vessel is making its way towards the site of the broken cables, aiming to begin repairs as soon as possible.
The repair ship, Telepaatti, departed from Turku on Friday and was seen on the VesselFinder website near the port of Kantvik, east of Porvoo, Finland on Monday afternoon.
The repair timetable is still up in the air, according to Jaakko Wallenius, the security director of Elisa, the operator of one of the damaged telecommunications cables.
"Repairs can begin after authorities have completed their work and when weather conditions are favourable," Wallenius said.
The Finnish Transport and Communications Agency Traficom is planning to inspect the Eagle S once investigators greenlight the move, the agency's maritime affairs unit chief Sanna Sonninen told news agency STT on Monday.
Traficom may order the vessel to correct any shortcomings it finds during the inspection. If serious shortcomings are found, the agency could potentially prevent the vessel from departing until necessary repairs are made, according to STT.
NBI: Damage likely caused by Eagle S
The NBI's Sami Paila said that investigators suspect the trail carved into the seabed was caused by an anchor belonging to the Eagle S.
"We were able to investigate this using the help of a submarine site survey. The effort was carried out in collaboration with the Coast Guard and the National Bureau of Investigation," he explained.
"I can say that we have a preliminary idea of what happened, how the anchor trail was caused," he said.
Among other tools, investigators used underwater cameras to examine the seabed in the Gulf of Finland. The Coast Guard ship Turva is near the scene with a team of investigators.
Earlier on Sunday, the NBI announced that investigators had not yet been able to determine where the ship's anchor had detached.
Windy conditions have hampered the investigation effort, according to Paila.
The poor conditions forced investigators to pause the subsea probe on Sunday, he said.
"Currently sea conditions are very difficult. We're completely at the mercy of sea conditions calming down, then we will continue the investigation," he said on Sunday evening.
Last week, investigators boarded the Cook Islands-flagged Eagle S suspected of damaging an electrical cable, as well as four telecommunications cables, between Finland and Estonia in the Baltic Sea on Christmas Day.
Authorities seized the Eagle S in Finnish waters off Porkkala, then moved the tanker eastward, anchoring it near the coast of Porvoo.
The tanker is thought to be part of Russia's oil-carrying 'dark fleet', also known as 'shadow fleet'.
New Zealand's Ministry of Foreign Affairs and Trade has said that New Zealand is not responsible for the Cook Islands-flagged Eagle S, according to RNZ.
According to the public broadcaster, New Zealand is concerned about Russia using the shadow fleet to circumvent sanctions.
The Cook Islands are a self-governing territory but also in a formal relationship with New Zealand, which governs the island's defence and foreign policy.
A spokesperson for the Ministry of Foreign Affairs and Trade told RNZ that it was aware of the incident, but emphasised that the country was not responsible for managing the Cook Islands' shipping register.