Breakdown of Der Einbrecher kann vermutlich durch das Fenster gekommen sein.
sein
to be
kommen
to come
können
can / to be able to
das Fenster
the window
Questions & Answers about Der Einbrecher kann vermutlich durch das Fenster gekommen sein.
Why do we have both gekommen and sein at the end of the sentence?
This is the Perfekt Infinitive, which is used to make assumptions about the past. To express that something could have happened, you use the conjugated present tense modal verb (kann) along with the past participle of the main verb (gekommen) and its helper verb in the infinitive (sein). We use sein here instead of haben because kommen is a verb of motion.
How certain is the speaker when using kann for an assumption like this?
When used subjectively, können expresses a simple possibility, roughly a 50 percent chance. It is similar to saying "could" or "might" in English. It shows much less certainty than muss (almost 100 percent certain) or dürfte (highly probable).
If kann already expresses possibility, why does the sentence also use vermutlich (probably)?
It is very common in German to combine subjective modals with adverbs like vermutlich or vielleicht to fine-tune the exact tone. While kann alone is just a raw possibility, adding vermutlich makes it sound more like a working theory or an educated guess.
Just as a quick refresher, why is it durch das Fenster rather than using the dative case for a physical location?