Breakdown of Кто-нибудь другой мог совершить это преступление?
этот
this [f: эта, n: это]
мочь
to be able to
другой
other
кто-нибудь
anyone / someone (unspecified)
Questions & Answers about Кто-нибудь другой мог совершить это преступление?
Our current lesson is about placing focused information (the Rheme) at the end. How would the nuance change if we moved кто-нибудь другой to the end?
The original sentence uses a fairly neutral word order for a general yes/no question. If you changed it to Это преступление мог совершить кто-нибудь другой?, the phrase кто-нибудь другой moves into the Rheme position and receives intense focus. It sounds more like a detective sharply highlighting an alternative theory: 'Could this crime have been committed by someone else?'
Why do we use кто-нибудь here instead of кто-то?
The suffix -нибудь is used for truly indefinite situations, like questions and hypotheticals, where you mean 'anyone at all'. If you used кто-то, it would state that a specific other person exists who committed the crime, but you just do not know their name. In a speculative question, -нибудь is the natural choice.
Why use совершить for 'committed' instead of a more general verb like сделать?
The perfective verb совершить is the standard, fixed collocation for carrying out highly significant, formal, or serious acts. You will almost always see it paired with words like преступление (crime), ошибка (mistake), or подвиг (heroic deed).
How does мог совершить express 'could have committed' without a 'have' plus past participle structure?