Riddle me that | Riddles Forum

Mr. Lincoln throws a party. In party comes a total of 4 guest:
1) His business rival, who is in a loss
2) A unskilled robber
3) A pregnant woman, poor in condition
4) Boyfriend of his old dead wife.

Every one was new to everyone. So, there was a total of six people in the party, 4 described above, Mr. Lincoln and his servant. Pregnant woman goes to Lincoln's room to tell how great the party was, but she found that whole room was misplaced and Mr. Lincoln was murdered. She screams and everybody runs here and there, somebody calls the police. Police arrives and see's that the room was alright and everything is placed at there respective places, yet the dead body wasn't moved.
Police find's a clue and arrest the killer.
Who is the Killer?

I don't understand how everyone was new to everyone. The business rival has a connection to Mr. Lincoln, and so does the boyfriend of the long dead wife. The servant must also no Mr. Lincoln. The robber was unskilled, yet everything was in the correct places. The pregnant woman should have died of shock or a heart attack. This is an interesting riddle, but it doesn't really add up.

Here is my suspect breakdown. The rival could have possibly attempted to steal documents in the office of Mr. LIncoln. The robber was unskilled, so he must have made a mess if he murdered Mr. Lincoln. The pregnant woman should have collapsed from shock. The boyfriend of Mr. Lincoln's old dead wife doesn't seem suspicious. The servant must have been bad if he let the pregnant wife in.

I think the servant was the murderer. The servant didn't prevent anyone from getting inside Mr. Lincoln's office. The servant must have been preoccupied with killing Mr. Lincoln.

Idea came to my mind but I failed to put it in a right way...

Idea was the only person alive who know the whole house well can arrange the room in no time will be the killer...

And yes you are right servant is killer and rest are just decoys...