aselem u aleikum, let me begin by saying ALLAHU 3ALIEM, ALLAH knows best.
there were many many reasons for certain peoples and groupes to raise up against uthman ibn affan may Allah be pleased with him.
I know that uthman radilahu anhu was killed on friday the 18th of dzoel hijjah 35 after hejra.(656 A.C.)
after the period of hajj much support came from the people of madina towards uthman ibn affan ra.this made it more difficult for the people planning on taking away from him his status as the khalief.
they tried to enter his house but the ansaar and the moehadjiroen fought back so at first they werent able to enter uthmans house.
then they burned down his house, climbed over the walls and attacked him while he was reading the holy quraan very calmly, it wasnt mohammed ibn abi bakr that hurt uthman ibn affan, it was al ghafiqi ibn harb that struck uthman with his machete he held in his hand.
after that someone else hit uthman with a sword, when the wife of uthman ibn affan ra tried to protect her husband, she lost her fingers in the act because someone had struck her too with a sword. the rebellions then hit uthman yet another time, this time it was a killing strike, they then plundered his house and the bait al maal.
these same wicked people actually allowed his funeral to be in peace that same night, uthman died 80 years old.allah yarhamo wa yarhaam al muslimeen ajdma3een.
i intentially did not mention anhthing on why he was murdered, because i agree with brother weakslave, this info really isnt beneficial, nor is it 100% facts.
all i can say is, it is absolutely wrong and ignorant if any muslim tries to make up any bad thing about this wonderfull man, who was guaranteed to be in paradise, his alias was dzoe noerain, the owner of 2 lights, because he was so lucky to be given both the prophet's daughters.may ALLAH bless all of them/
some say oethman in comparison to omar ibn khattab was too easy in his attitude, this causing the muslims with weak imaan to do or neglect certain things..allahu 3aleem.
an example of this is , he alllowed the companions of the prophet salalahu wa3alyhi weselem to emigrate to other cities and countries , he also allowed them to have their own properties etc..which in the time where omar ibn khattab was the khaliefa was impossible.
may ALLAH be pleased with all of them, we should learn who they are, what they have done for us, etc etc etc