Task: Question Generation
Input (English): Passage: An older couple, Frank and Mary Sylvester, are cooking food over a campfire. Unbeknownst to them, they are being watched by a mysterious figure in the shadows. While Mary is taking a walk in the woods, she hears her husband scream and returns to the campsite to find her husband's decapitated corpse. She is then killed by the killer wielding her husband's axe. 
Several weeks later, three teenaged couples are hiking in the same remote forest high in the Colorado Rockies to enjoy the nature and to spend time together. As they progress deeper into the wilderness, it becomes clear that the killer is stalking them. During their first night in the woods, Gail hears a noise and sends her boyfriend Greg to check out the disturbance. While isolated, they are both murdered by the killer.
The next day, their friends Nancy, Bobbie, Skip, and Joel find the couple's gear missing and assume that they have turned back and gone home. Skip and Joel decide to head for the infamous Suicide Peak to do some rock climbing while the girls suntan. Meanwhile, forest rangers Lester Tile and Mark O'Brien get a phone call about the missing Sylvester couple, and Mark heads into the forest to investigate. Before leaving, Lester tells Mark a story about a Gypsy boy he once saw during a forest fire years ago. The boy was covered in burns, horribly disfigured, and left for dead.
Output (English): What are the full names of the people called about the older couple?