A recent Roseburg High School graduate with ambitions to go into the military remained in serious condition this morning at a Springfield hospital after he was injured in a rollover accident Saturday evening that killed another Roseburg teen. Hector Mandera, 18, suffered a fractured skull in the accident and is in the intensive care unit at Sacred Heart Medical Center at RiverBend, his grandfather, Joe Mandera of Umpqua, said this morning. Eighteen-year-old Kaylyn Dawn Oelrich died in the crash around 11:20 p.m. Saturday in the 4700 block of Happy Valley Road in Green. Oelrich was driving a Kia SUV when …