Assessing a potential supervisor who had a fallout with a previous PhD student I am a PhD student and I have been thoroughly searching for future supervisors. 

I have been speaking with current PhD students about a certain professor to get to know more about them, and they let me know their experiences as well as the experience of a previous student. 
Apparently, it seems this previous student had some major problem with the supervisor and left in an ill manner (e.g., as soon as the PhD was finished, they left not teaching the new students after them how to use the equipment they built).
The PhD Student I had this conversation with is a respectable one, and I strongly believe they were having a serious conversation with me.

This professor under question so far is a great person, and I am incredibly happy to be working with them soon, and as far as I know and can see, they are attentive, supportive, encouraging and very willing to take suggestions from their team. 

This conversation I had with the PhD student worries me slightly and due to the professor’s kindness, it makes me even more anxious to find out the professor’s side of the story, and what they thought about it.
However, I am too anxious/embarrassed to bring it up. 
I have been thinking of having a one-to-one meeting with them and asking them a few questions I could frame as a “mini interview I like to take of future supervisors”:


  Have you had any unpleasant experiences with PhD students in the past?


but I was wondering if the academic community on here would have better/more suggestions?
I have been thinking of having a one to one meeting with them and asking them a few questions I could frame as a “mini interview I like to take of future supervisors”: “Have you had any unpleasant experiences with PhD students in the past?” but I was wondering if the academic community on here would have better/more suggestions? Maybe even a view point of a professor?


Ok, don't. You don't like to be lied to your face, and probably your supervisor also doesn't like it. And maybe your supervisor is not stupid and may realize something’s up.

Let's just consider the possibilities (and to be clear, I have seen all of these):


Your supervisor is a psychopath who behave nice as long as it serves them and shit people in the face to get what they want if they can. These are very good liars. On the other hand, they don't care if you recognize them for what they are, they just will adapt the strategy. 
Your supervisor is a person who doesn't plan his PhD supervision very well, and sometimes if results are not coming in puts all the blame on the student.
Your supervisor and the previous student just did not get along due to their personalities or their goals not aligning, and the previous student interprets this very much one way.
Your supervisor decided at some point to pressure the student with good intent e.g. to help them, and the student took it personally.
The student somehow messed up and put the blame to the supervisor.


What to do: 


The most dangerous for your scientific career is 2. Here, check if you have the feeling that your supervisor really tries to generate a good context or if you are working alone and uncoordinated.
I would not necessarily care about 1; these are people whom you can bargain with if you have something in your hand, but check how valuable you and your result are and how much depends on you.
Number 3 you can address by discussing expectations and goals (35 h peer week, one conference publication vs. 60 h per week, two nature papers) early in the thesis.
Number 4 depends on the cultural context, but is maybe not that bad at all. (While my professor probably saved my thesis by pressuring me to finish the thesis, he probably messed up his working relationship with another PHD student by doing exactly the same thing so much that the student essentially dropped out.)
Number 5 is irrelevant to you.