Here is a translation of the linked Swiss report dated 15Aug:
An investigation.
Place, date and time: 500 m southeast of Segnaspass (GR), August 4, 2018, 16:56 LT
Aircraft
Enrolment: HB-Hot
Samples: Junkers aircraft and engine Works AG, Ju-52/3m G4E
Holder: Association of Friends of the Swiss Air Force (VFL),
Via Landstrasse 271, 8600 Dübendorf
Owner: Swiss Air Force, P.O. Box 1072, 8600 Dübendorf
Pilots: 2
Cabin Crew: 1
Passengers: 17
Flight:
Flight rules: Visual flight Rules-VFR
Mode of operation: lucrative
Begin of departure: Locarno (LSZL)
Destination: Dübendorf (LSMD)
Damage:
Crew: 3 fatally injured
Passengers: 17 fatally injured
Third parties: None
Aircraft: Destroyed
Third-party damage: low Floor damage
Short Description: The plane flew on a northeast course in the basin Southwest
of the Piz Segnas. Against the northern end of the basin
It started a left turn that turned into a spiral trajectory
Developed against the bottom. A short time later, the plane collided almost
perpendicular to the terrain.