Czech has no articles, so it does not use words like the or a/an.
So:
English needs articles here, but Czech usually does not.
Zná is the 3rd person singular present tense form of znát.
So:
Here it agrees with policie, which is singular:
Because dobu is the accusative singular form of doba.
The noun doba is the direct object of zná, and direct objects often go in the accusative.
So:
Because krádeže is in the genitive singular.
It depends on doba:
So the structure is:
This is very common in Czech noun phrases.
In isolation, krádeže can have more than one grammatical use, but here it means genitive singular: of the theft.
Why not plural?
Because the phrase is doba krádeže, meaning the time of the theft. That relationship naturally calls for the genitive singular.
So in this sentence, it is understood as:
That is a very natural question, because English often uses know for both.
In Czech, znát and vědět are different:
Czech often says things like:
So zná dobu krádeže is normal Czech.
In context, it usually means the time when the theft happened or the time frame of the theft, not necessarily the length of the theft in minutes.
So depending on context, it could mean:
In police or formal language, this kind of phrase is common.
No, Czech word order is more flexible than English, because the cases show the grammatical roles.
The neutral order here is:
But other orders are possible for emphasis, for example:
That might emphasize the time of the theft.
So the original sentence is a normal, straightforward order, but not the only possible one.
Not necessarily. It is capitalized here simply because it is the first word of the sentence.
In the middle of a sentence, policie would normally be lowercase unless it is part of an official name.
For example: