BROWNSVILLE, Texas—The defense department says it is investigating reports of a Mexican military helicopter seen flying in Texas.    Zapata County Sheriff Sigifredo Gonzalez says several people reported seeing the aircraft on Sunday flying over an RV park near Zapata, some 100 miles northwest of McAllen on the border with Mexico.
   Border Patrol spokesman Jason Darling says the Mexican military is conducting operations near Zapata along the Rio Grande.
U.S. Department of Defense spokeswoman Maj. Tanya Bradsher says the flyover is under review.
     The press relations department duty officer at Mexico's Defense Department told The Associated Press Friday that she has no information on the reports.
   A Mexican military helicopter was also spotted March 10 over Zapata County.