The sister of a former University of Illinois student convicted of killing a Chinese scholar told a jury deciding whether he should be executed that he was a "very gentle person" who never raised his voice.

File photo of Brendt Christensen by VCG

Andrea Christensen was the last witness that lawyers for Brendt Christensen called to the stand Monday. The defense plans to rest its case in the penalty phase on Tuesday.

Earlier Monday, Christensen's mother, Ellen Williams, testified that the 2017 slaying of Yingying Zhang was "horrible" and she feels "bad." But she said it would be devastating if her son receives the death penalty.

Christensen did not testify.

The federal jury that found him guilty last month now must decide his punishment.

Rebuttal witnesses will be called Tuesday. Closing arguments are scheduled for Wednesday.