They would trace the serial numbers and license plates on the tools and the hydraulic ladder truck to figuire out who they hired/bought it from then check surveillance around those times which would lead them to other clues like vehicles, people who would get further investigated until they pin point the thieves.
We use same stihl concrete saw for work occasionally with the right blade it will cut just about anything. Looks like they used a blowtorch also. There is nothing that museum could have done tbh short of having armed guards with permission to shoot. But they are too woke and thieves took advantage of that.