With that level of destruction this was without doubt an overload, a rather severe overload. I would suggest that you not even waste a minute contacting S&W, you need to go straight to the ammunition manufacturer and ask for contact information for their insurer. Because you are not only owed the funds for a new pistol your brother is owed for Pain, Suffering, and Medical Care.
As for how this could happen, before this thread was locked yesterday I did some looking into how it could happen using Titegroup as an example. BTW, Titegroup is quite popular with high volume reloaders because it's very economical with distinctly low charge weights per load.
So, according to the Lee 2nd the useable volume of the 40 caliber case is 0.69cc with a 180 grain bullet installed to an overall length of 1.125 inch. By my measurement using a cheap syringe purchased at a gun show as a grease applicator the total volume of a 40 caliber case is approx 1.1cc. The maximum charge for a 180 grain bullet using Titegroup is 4.7 grains and that charge has a total volume of 0.40cc. So, right off you can load a 72% overcharge before you start to compress the powder charge. Put a double charge into the case and visually it will only appear a bit more than 2/3 full, so a double charge of Titegroup will fit easily with no chance of overflowing the case.
What I suspect happened is that the reloader was using a progressive press and he was interrupted or distracted at the point where the press is indexed. As a result the handle on the press was pulled twice without the shell plate on the press indexing between pulls. The result of doing this is a double charged case with the result of exactly what you have posted in your pictures.
It's why I do not have one single bottle of Titegroup in my powder inventory. Even after starting to reload the 380 ACP recently and with Titegroup being a nearly ideal powder for this caliber. Because this particular powder has a distinct reputation for being involved in overcharge events. If you want to see actual examples of this, simply do a google search for "Titegroup overcharge" and you'll find over 3000 results. BTW, I'll leave you to sort through those results but expect you'll find many similar to what happened to your pistol.