Nearly 140 tandem skydiving instructors will have to undergo retraining in the wake of a jump in Northern California that left two dead.
The United State Parachute Association announced Thursday that a number of instructors and candidates will be retested and retrained on proper emergency procedures.
The association's website says two instructors were either not properly taught or certified.
The USPA also says "post-course rating applications may have been submitted with forged signatures since the course examiner was suspended and not authorized to conduct courses."
The move comes nearly a month after 25-year-old Yong Kwon and 18-year-old Tyler Turner died during a jump near Lodi after their parachute didn't deploy on August 6.
The USPA has no records that Kwon was certified. In the wake of the deaths, the organization concluded that a number of candidates who attended tandem instructor courses were not properly certified.