A few days ago I killed Ma'zaka, the Khajiit who works in the Solitude lighthouse. After he was dead, I took some money from the chest in the sleeping quarters and an Orcish sword off of the table near the door. Shortly after, I was attacked by a group of bandits who, a note would reveal, were sent by Ma'zaka.
I really don't know how he pulled that off.
There was a long lasting soul trap placed on him by a demora, and after escaping the realm he brought to, he found himself in the sphere of sithis. In exchange for the heart of the dremora who captured his soul, sithis agreed to send assasins in your direction
or
You thought you killed him but really he was slowly bleeding out. With his dying efforts, he managed to sign off a contract which he left with his grossly mutated sibling who hid under the floor. Upon hearing that the contract was not honored beyond death, he vowed to end your life, and the life of all assassins associated with the crew they hired. Beware of the one with gnarled teeth....?
Sorry. For some reason I am avoiding sleep.