Nikolas Cruz, who murdered 17 pupils and staff with a semi-automatic rifle at a Florida high school, was formally sentenced to life in prison on Wednesday.
A jury voted last month to spare Cruz, 24, from the death penalty, instead choosing life in prison without possibility of parole for one of the deadliest mass shootings in US history.
Grieving relatives of the 17 pupils and teachers killed in the 2018 high school shooting in Parkland, Florida, confronted the gunman, Nikolas Cruz, with tearful, angry words at his sentencing hearing.
“You are pure evil,” Anne Ramsay, the mother of murdered Helena Ramsay, 17, told Cruz.
He pleaded guilty last year to premeditated murder.
Cruz listened to the victim impact statements in the courtroom, wearing an orange prison jumpsuit, large spectacles and a Covid-19 mask.
Inez Hixon called Cruz a “domestic terrorist” for killing her father-in-law, school athletics director Chris Hixon, two other staff members and 14 pupils with a semi-automatic rifle at Marjory Stoneman Douglas High School in Parkland, about 50 kilometres north of the courthouse in Fort Lauderdale.
“I wish no peace for you,” Ms Hixon said in an emotional testimony. “I wish nothing but pain. And I hope that every breath you take, you remember that's a breath that you stole.”
Cruz was 19 at the time of his attack and had been expelled from the school.
Some of the survivors organised a youth-led movement for tighter gun regulations in the US, which has the highest rate of private gun ownership in the world and where mass shootings have become common.
Many family members who sat through the three-month penalty trial said they were dismayed by the jury's decision to recommend life in prison without possibility of parole instead of the death penalty.
Fred Guttenberg, whose daughter Jaime was killed in the shooting, said on Twitter that he would not speak during the hearing.
“Because I have decided that it simply won’t change reality or the way I feel,” Mr Guttenberg wrote.
“The reality is that I will still visit Jaime at the cemetery and the monster's fate will not change. It has already been decided.”
Reuters contributed to this report