Breakdown of Vem är det som anklagar mig?
vara
to be
vem
who
mig
me
som
who / which / that (relative pronoun)
Questions & Answers about Vem är det som anklagar mig?
Why say Vem är det som anklagar mig? instead of just Vem anklagar mig?
Both mean 'Who is accusing me?', but the longer version is a cleft sentence used for emphasis. Similar to 'Who is it that is accusing me?' in English, this structure is very common in spoken Swedish to express surprise or indignation, which makes it a great fit for defensive or rhetorical questions.
Can I skip the word som here?
No, som is mandatory. Because the question word vem acts as the subject of the action (the one doing the accusing), you need som to connect the two parts of the sentence: Vem är det and anklagar mig.
If I wanted to say what I am being accused of, how would I add that to the sentence?
You use the preposition för. To say 'Who is it that is accusing me of the crime?', you would say Vem är det som anklagar mig för brottet?.