P.R. Laws Ap. tit. 34A, § II, Rule 157
2019-02-21 00:00:00+00
Upon a trial for murder, once it is proven that the death was caused by the defendant, the burden of proving circumstances of mitigation, or that justify or excuse it, devolves upon him, unless the proof on the part of The People tends to show that the crime committed only amounts to manslaughter or that the defendant was justified or excused in committing it.