I just found a Lear 45 Airplane Flight Manual (instruction book), the accident plane was a Lear 35, but I assume it was similar.
Here is the whole AFM https://hangar45.net/wp-content/uploads/2017/10/learjet-45-afm.pdf
Here is the page that answers your question, as the bank angle goes up, the stall speed goes up, follow the dotted line:

I might have mentioned before that I (used to) spend a lot of time reading Airplane Flight Manuals, sometimes known as Pilots Operating Handbook (POH). I used 85 different POHs building one of my Apps. I like reading these things
Here is what Stall Speed definition looks like in a Cessna 182T, 4-seat single prop plane that I used to fly.
Expressed by numbers in a table. A different format than the graph format used in the Lear above.
