Police are investigating the possible murder of an American couple still missing after three fugitives stole their yacht last weekend while it was docked in Grenada, according to the New York Post. Ralph Hendry and his wife Kathy Brendel were last seen on Sunday on the island Grenada, the same day the three fugitives escaped custody. The police have yet to identify the couple, but Hendry’s sister, Suellen Desmarais, told ABC News that the couple’s neighbor noticed their boat missing on Monday morning. Ron Mitchell, 30, Trevon Robertson, 19, and Abita Stanislaus, 25 were being held on robbery charges, while Mitchell faced additional counts of rape, attempted rape, and indecent assault. The three men successfully escaped to St. Vincent and the Grenadines, but were then arrested. Grenada Police are “currently working on leads that suggest that the two occupants of the yacht may have been killed in the process,” authorities said. According to a statement from The Salty Dawg Sailing Association, a sailing organization the couple belonged to, a good samaritan who boarded the yacht when it was re-docked discovered “evidence of apparent violence.”