Brutus was tricked into killing Caesar by other conspirators. These people are not justified in killing him, because they were envious of his rule instead of them being king. They also did not like the idea of a one-man rule, and wanted Pompey to still rule with Caesar. Brutus killed Caesar because he was given false information that he would try to harm Rome. Brutus was just being a loyal citizen and defending his country from Caesar, and did not know the truth. This is why he is justified in killing Caesar.
The mice picked the lion up from the flower field, and managed to pull the lion out of the flower field so the lion wouldn't go into an eternal slumber.
