Murder, sinful.
The laws of this world still remained at a relatively primitive level—enshrouded beneath a veneer called civilization. Their primary use was to maintain the status of the upper class, rather than justice.
If the man had saved a noble instead of his own daughter, even after killing several thugs, and with a noble on his side, he could easily have wiped clean the fact of murder. Not only would he be innocent, but if that noble were kind and benevolent enough, he might even have received a substantial sum of money.
But regrettably, he had saved only his own daughter.
No matter what the man's motives were, he had violated the law, and at most because his opponents were thugs, a part of his punishment might be reduced, and then lessened further due to the sympathy of the judge and jury.