I'm writing a novel and have a complicated criminal case to bring to a close in a court scene. I have a bunch of questions about how the case (or cases) would work based on the specific events of the story and I also want to check some things are reasonably believable. The story takes place in a made-up country in the future where technology is similar to ours, so there is some flexibility. Forgive me if this is not an appropriate place to ask or if my questions are plain stupid. My jury duty was cut short, so I missed out on a lot.
First, the relevant points of the plot:
Bad Guy (BG) assaults Secondary Character (SC) with a knife with intent to kill and Main Character (MC) saves SC. Neither of them know who BG is. No other witnesses.
SC is a homeless, illegal immigrant who is hiding from the police. SC moves in with MC for a while and they don't report the incident to the police.
Two weeks later, MC and SC find the knife BG used to assault SC. It has BG's name engraved into it.
MC identifies who BG is and assaults BG out of rage. BG gets enraged and assaults MC with a knife. MC is now fighting out of self-defence.
During the fight, BG confesses to trying to kill SC and admits to killing other people in the past, which was previously unknown. BG stabs MC with the knife, nearly killing them. SC is the sole witness to the stabbing, but not to the fight.
BG then tries to kill SC with the knife but is arrested by more witnesses that arrive on the scene. MC survives and both they and BG get hospital treatment and are questioned by police.
MC admits to assaulting BG, but claims that BG was unreasonable to stab them with intent to kill.
SC backs MC up and claims that they were assaulted by BG two weeks ago.
BG claims that they were practicing self-defence as it was MC that assaulted them first.
During the investigation, the police find evidence (ID, personal belongings) that BG may have kidnapped, abused, and then murdered several other people a few years ago.
Ideally, for the climatic court case ending: BG goes to jail for the assaults on SC and MC, and killing several other people. MC gets pardoned for his assault on BG.
Now for the things I am unsure about:
Realistically, assuming the court isn't too busy, how soon can the court case begin after the police investigation ends? Less than 2 or 3 months?
Ignoring the fact that SC is an illegal immigrant, would they be allowed to continue residing in MC's home, or is there any reason the court wouldn't want them to be together?
Who gets charged for the most recent incident? Can BG charge MC for the initial assault, or would they be ignored and MC or the police get to charge BG for attempting to kill MC?
Would MC and SC be able to charge BG for the assault on SC two weeks ago in the same case, or would that be a separate case?
Can MC use the unconfirmed evidence about the other murders against BG in court? If not, do they first have to do a separate court case to find out if BG is guilty of those murders?
If BG can be proven guilty of all his crimes, can the sentencing be immediately after the jury declares guilty, or would there need to be some time for the judge to decide after the verdict?
I think that's it. I'll edit in more information or questions in if needed. Very sorry for the wall of text or if this is way too much and stupid.