Lincoln, Neb.  Nebraska Head Wrestling Coach Mark Manning announced Thursday that Justin Ruiz will return to Nebraska for the 2001-02 season after spending two years on a Mormon mission in Chile.  Manning said he received the letter of intent from Ruiz Wednesday evening, the final day of the early signing period.    Ruiz redshirted during the 1998-99 season, while compiling a 12-3 record in open tournaments for the Huskers.      Ruiz, the nation's top high school prospect at 190 pounds in 1998, was a three-time Utah high school state champion at Taylorsville High School in Murray, Utah, for coach Mark Campbell.  He was selected as the National Wrestling Hall of Fame's High School Wrestler of the Year in 1998.  Ruiz also captured 1997 Junior National Greco-Roman and Freestyle titles at 191.5 pounds.    According to Manning, Ruiz will strongly compete for the void left by NCAA champion Brad Vering, who will complete his eligibility this season, at 197 pounds next season.  Ruiz was a U.S. teammate of Vering at the 1997 Junior World Championships.    "Justin Ruiz has the characteristics we are looking for in a student-athlete," Manning said.  "He is a great student, serious about being the best wrestler in the country, and he is a classy kid."    Nebraska opens its home schedule Friday night against Wyoming at the NU Coliseum starting at 7:30 p.m.