I speculate in line with OD100's probable theory. Mainly because the Piper Seneca has proven to be a rugged, reliable airframe, produced since 1971, and used in many countries as a multi engine trainer.
Notwithstanding some sort of gross maintenance/overhaul negligence, it is least likely for the airframe to have suffered catastrophic failure on its own.
Catastrophic airframe falure can occur rapidly in any airplane with improper control inputs, especially when exceeding airspeed limitations. Operating limitations can be exceeded in seconds from a resulting dive, spiral or spin without immediate corrective control inputs.
Even without flight data recorders, trained accident investigators can usually trace the probable inflight break-up sequence by studying the metallurgy, ripped airframe parts, deformations and by correlating the debris pattern.