A roof fall occurred in the 5 East Panel at cross-cut #17 in 1/2 the intersection of #3 entry extending 10ft. into the pillarline toward #2 entry. The fall measured approximately 20ft. x 20ft. x 5ft. The area was supported with 5 ft. fully grouted roof bolts and 9 ft. mega bolts. An undetected slip was determined to be the cause of the fall.