PA-23 pilot reported the nose gear collapsed during landing rollout. Once the aircraft was stopped; the left and right main gear also collapsed.

Narrative

Day of the incident:Preflight inspections were performed. Aircraft was fueled prior to flight. Departed. Normal flight. Returned to origin airport. Cleared to land. Gear safe indicator lights were three green. Nose gear was visible in the down position from the mirror on the left inboard nacelle. Normal landing. During the rollout the nose gear collapsed. I immediately shut the fuel off; mags; avionics and master and promptly exited the aircraft. Fire Rescue personnel responded. During the removal of the aircraft from the runway; the left main gear collapsed while still on the runway prior to being towed. This was then followed by a right main gear collapse when the aircraft was clear of the runway on the taxiway.Day before the incident:Post maintenance flight to nearby airport after power pack replacement and hydraulic work performed. Full stop landing and taxi back. Took off for another intended full stop; that landing was aborted due to unsafe nose gear light. Initiated go around. Another low pass by tower showed gear down. Returned to origin of departure and gear indicator lights showed three green. On final; nose light flickered. Normal landing. Upon exiting runway while on taxiway; nose light was not indicating properly and was not on during taxi back to hangar.Maintenance personnel were notified and inspected aircraft to find indicator needed to be adjusted for proper engagement. Repaired; returned to service; given log entry. After departure in route to destination airport; cycled gear to make sure all ops were normal; which they were. Three green and visible nose wheel in down position. Normal landing at destination airport. No anomalies.Personal logbook flight entries have always been recorded to the best of my knowledge for maintaining currency and accuracy.I am filing this report due to a potential safety issue regarding the aircraft.