An 1801 Whodunnit

Say you're on a jury in 1801 Massachusetts.

On trial is a young man accused of killing his sweetheart. Her family did not approve of their connection.

On the day in question, he had told two witnesses he passed on the road that he was on his way to her house to rape her (and thus force the family into letting him marry her).

Her body was found in the field beside her house with multiple stab wounds in the arm, side, breast, neck, and back. The accused stood nearby with blood on his clothing and holding a knife that was later matched to the wounds.

The accused said he was Not Guilty because ... the girl had done it to herself.

Her motive was shame over her ruined reputation - he had told her he bragged to several other men that he had been having sex with her, and in response she had committed suicide.

It was well known that the accused did not have the use of one of his arms, due to a frozen elbow joint since childhood.  How could he have stabbed her successfully all those times using only his other arm?

And two neighbor girls had been outside that day, and had heard shouting, but not such that they thought someone was being murdered.

Were they lying because they didn't want to admit they had heard such screams and done nothing?

But if the girl had done it to herself, how did she manage to stab herself in the back?

And if he loved her, what was he doing in that field in any case, since according to either explanation of events it meant physical or emotional harm to the girl?

Would you find him Guilty or Not Guilty?