In English, we might ask a question that that insinuates an answer, in a sort of sarcastic way, made more as a statement than a question: "What could/would have a policeman been doing in a donut shop?" Like, "I can't imagine what on earth they would have been doing there!" In these cases, "could" and "would" are used interchangeably.
How would one make this type of statement in Spanish?
EDIT: Clarification: As Pablo brought out in his answer, I should clarify that I'm talking about conjecture regarding a factual event that has happened.
Now, in English one can make a distinction between whether the event occurred in the past or is a current event:
"What could the policeman be doing in a donut shop?" "What could the policeman have been doing in a donut shop"
The first regards an event happening now. The second refers to an event that already happened. Both cases the question is about motive.
In Spanish usually one hears this expressed in the following manner, : "Será?"- Could it be? "Que pensarán de la situacion?" - I wonder what they're thinking about it.
These are basically a present-tense type of construction (using a future tense in a present tense way.)
My question is whether there is a past tense equivalent in Spanish that conveys that same conjecture about an event that occurred previously.
Second update: aparente brought up a second point that I should have clarified: Yes we can use "habrá sido" "habrá entendido"to discuss past events, but I wondering whether there is a past-tense equivalent where the verbs themselves are in past tense (not the future tense like "será" "habrá".)
Third update. Nevermind, I didn't understand my own question. Both English examples the questions themselves are in present tense, hence so they are in Spanish. ..... Thanks for everyone's responses.