Two Kennedy's and Marilyn Monroe

I was watching a special on ABC a month ago about Marilyn Monroe's death, it may have been the aniversary of her death. Anyway, it was always thought that JFK was responsible for her death.
I think he may have gotten her pregnant. In one of the autopsy photo's she has a scar on her lower belly. During the ABC special, they never talked about the scar, they avoided it. Why? I think a scar on her lower belly would have had some explanation. What if this scar was from an abortion. Maybe this was JFK's baby and she was forced in a way to have an abortion. Feeling guilty, she calls him or Robert Kennedy threatening to break open the whole thing. The affairs with both brothers or just JFK and the abortion. Can anyone tell me what the scar was on her lower belly in the autopsy photo's? was it some type of surgery and i am wrong about the abortion?
Also, when Robert Kennedy was running for president or senator, he made an appearance at a Yankee's game I think and Joe Dimaggio was there as well. When Robert Kennedy walked up to shake hands with him, Joe turned the opposite direction to avoid him, didn't even look him in the eye. It was an odd moment. He wanted nothing to do with Robert. Was Joe upset about how the brothers treated Marilyn as a toy or did Joe know something? I don't think Joe ever wrote a Bio, it would have been pretty good.