I need help with a mystery I'm writing!?

http://www.johnmorganwilson.com/writingcraft.htm

http://keepmeinsuspense.blogspot.com/2006/07/plott...

http://www.yale.edu/ynhti/curriculum/units/1989/4/...

Mysteries work through delayed revelation.

So, perhaps two people were in the house on the night of the murder other than the murderer. One was going to rob the house, and found the door open, while the other, someone the victim trusted and let in their house, actually just walked in and did the murder.

The would-be thief broke out the window out of fear of being discovered with his stolen goods, while the actual murderer took the keys and locked the door, leaving a seemingly impossible scene with the window broken from the inside but the door locked and unforced.

You as the writer would know all this, and your detective and reader would have to figure it out.

This scenario I made is simplistic and possibly transparent, but entirely logical in retrospect. Which gives you an idea of how you could work with something similar, but less obvious, that could still be explained in retrospect, which is how most mysteries work.

The man who entered had a companion. He had a laser through which he broke the glass and asked his companion to go and break it on the sidewalk so that the detectives get confused. But unfortunately he left his laser over there. The detective found the laser which had is fingerprints. He checked the fingerprints with everybody in the country with the help of police. Then he checked his and it matched and he went to jail for 2 months. After he came outside he saw that his assistant became a very rich man. Then he found out that the assistant was the culprit and told the police and got evidence by saying that half of the fingerprints in laser didn't match his. then the police arrested the assistant and interrogated him but he didn't answer. Atlast after several beats and punishments, he said that he put the detectives hand around the laser while he was sleeping and the companion with him was his brother as they came to steal money for their sister's eye operation. And then the detective was back to his post and he was awarded the noble detective award for solving this great case.

you could have it go that one of the people that was REALY close to the person who was robbed went "missing " but they stole the item the acted like they where kid naped...