According to Bob Shock's testimony (he was running 494). He saw the curve ahead of 483 begin to kick out ahead of 483. He turned to his fireman saying "hang on we're going on the ground". At that instant there was a huge BANG and the slack ran in hard. By the time Bob looked back ahead, the 483 was gone from his sight. Clearly, 494 shoved 483 off the side of the fill and over on its side. It happened so fast, there was nothing anyone could do about bailing out. Paul Mayer was firing 483. He ended up under the engine, probably killed instantly.
When I asked the Alamosa Old Heads about this derailment. No one wanted to say much about it. Jim Pearce was working out of Durango then, he said everyone liked Paul Mayer, he was a "good kid". When I inquired about train handling being the cause, they all clammed up. Bob Shock' statement clearly avoided the issue, concentrating on the curve licking out. I later heard some comments about Bill Holt's train handling in other conversations, but no one would say anything in conjunction with the wreck. One thing I heard was Holt was in the habit it of setting the engine brakes to trim up his speed going down hill. One always keeps the engine brake is release on down grades, it helps keep the slack stretched. One person (not one of the Old Heads) suggested that if the engine brakes were applied to strongly, the force of the brake shoes against the drive wheels would keep the drivers from "floating" in the frame to accommodate the curve, possibly making the curve kick out. Who knows, Bill isn't around to defend himself, and I'm not going to point any fingers.
But clearly, having 494 behind 483 made a simple derailment of 483 into a big disaster, and the last fatal accident on the narrow gauge when the D&RGW owned it.