The Russian-crewed freighter that sparked a high-seas mystery when it disappeared nearly three weeks ago has been found by a Russian naval frigate off the West African coast, the country's defense minister said Monday, according to Russian news agencies. The Arctic Sea's 15 crew members, last heard from July 28, were alive and now aboard the navy ship, Defense Minister Anatoly Serdyukov said. He did not give details about what happened to the ship, saying the full story could be made public later Monday, according to the agencies. The crew had reported being attacked on July 24 in the Baltic Sea by masked men who beat them and questioned them about drugs before leaving 12 hours later, Swedish police have said. The Russian minister said crew was not under armed control when the ship was found around 2100 GMT Sunday some 300 miles (480 kilometers) away from the island nation of Cape Verde. "The crew is alive, all are alive and healthy," Serdyukov was quoted by the RIA-Novosti news agency as telling President Dmitry Medvedev. The crew members were taken aboard the Russian navy frigate Ladny, Serdyukov said, according to the RIA-Novosti, Interfax and ITAR-Tass news agencies. The disappearance of the 98-meter (320-foot) Arctic Sea perplexed experts and officials across Europe, with speculation about what happened ranging from its being seized by pirates to being involved in a murky commercial dispute. It had been due to dock Aug. 4 in an Algerian port, but its vanishing brought little attention until Medvedev last week ordered the Russian military to take "all necessary measures" to find the freighter. Cape Verde is about 2,500 miles (4,000 kilometers) southwest of Algeria's coast. Finnish investigators reported Saturday that the ship's owners had received a ransom demand. But it was not clear if the demand came from people who actually held the ship, or from opportunistic charlatans.