The following text is from Aviation Week:
02/08/60. After completing 21 successful flights of the Army's test
program in the preceding six weeks, the aircraft was destroyed at
Moffett Field, California, USA in early 1960 when it pitched up 180
degrees and dived 5,000 ft (1,524 m) to the ground in an inverted
attitude. The aircraft had been just turned over to NASA for
further testing. The NASA test pilot ejected at 1,000 ft (305 m)
and suffered a sprained back.