Crime and danger (убийца, поймать)

An Aspect Pair Worth Learning Together

Убивать (imperfective) and убить (perfective) work like every pair you have met: the imperfective for the activity or a repeated act, the perfective for the single completed one.

В этом фильме долго *убивают время. — activity Он убил час на дорогу.* — one completed act

Note that Russian, like English, uses this verb for time as well as for people: убить время is to kill time.

Ловить and Поймать

The same pattern again, and the two verbs are not built from one root: ловить is the trying, поймать the catching.

Кот *ловит мышь. — is chasing it Кот поймал мышь.* — has got it

Живой and Мёртвый

A hard pair, and both are ordinary adjectives. Живой also means lively — живой разговор, a lively conversation — and мёртвый turns up in fixed phrases like мёртвая тишина, dead silence.