School shooter Nikolas Cruz could face the death penalty after pleading guilty to killing 14 students and 3 teachers at a Florida high school in 2018.
Cruz opened fire at the Parkland, Florida secondary school on February 14, 2018.
He pleaded guilty to all 17 killings and 17 more attempted murders of those who survived the appalling assault on Marjory Stoneman Douglas High School.
Florida authorities are seeking the death penalty.
Then 19, Cruz entered the school with a legally bought semiautomatic weapon and killed 17 people on Valentines' Day 2018.
Mobile phone footage filmed by survivors showed Cruz warning his victims: "You're all going to die."
Judge Elizabeth Scherer read the victim's names one by one as he repeated "guilty" after every one. That included the 14 students he killed, 3 teachers and 17 shooting victims who survived the onslaught.
Cruz's guilty plea will help him in his effort to avoid the death penalty.
From the beginning of the trial three years ago, Cruz's lawyer said he would plead guilty in order to seek life imprisonment - rather than death.
State attorney Michael J Satz said he will be pursuing the death penalty.
Legal experts believe a guilty plea can help avoid that fate.
Cruz told the court he was truly sorry for the shootings.
He addressed the judge and said: "I am very sorry for what I did and have to live with it every day.
"If I were to get a second chance, I would do everything in my power to help others."
The new charges add to Cruz's legal problems after he attacked a prison guard.
Cruz was given a 26-year sentence last week for attacking a jailhouse guard nine months after the school shooting.
That ruling could be an "aggravating factor" behind giving Cruz the death penalty.