So all homicide cases should be held Federal Courts?
You are correct. This is another misconception out there. That "Federal offense" means "Serious offense." Wrong. Most federal statutes are bizarre legal cobbled together creatures involving state lines, telephone lines, or the high seas. Murder, kidnapping, arson, rape, etc. are all state matters. The best example: remember the "Mississippi Burning" civil rights murders. The state refused to move, of course, so the fed gove stepped in and convicted the killers. The charges? Depriving a citizen of his civil liberties. The G did NOT charge them with murder because they COULD NOT charge them with murder. The g's case amounted to "You deprived them of their liberties by murdering them." but there was no murder charge.
Ofcourse not.
We are talking about checks and balances.
On a practical level, local crimes are dealt with locally.
However, a murder must be considered a crime in every state, no state can pick and choose to ignore a murder and redefine the term to mean what it wants to e.g. it is not 'murder' to kill deformed infants.