Miami man pleads guilty to 2012 murders of his wife and her 2 young daughters; death penalty could be on the table

A Miami man pleaded guilty Friday to the 2012 murders of his wife and her two young daughters, accepting responsibility more than a decade after the crimes.

Alberto Sierra, 42, stood in a Miami-Dade County courtroom and entered guilty pleas to three counts of first-degree murder, burglary, three counts of kidnapping and two counts of abuse of a human corpse.

When asked by Miami-Dade Circuit Judge Marissa Tinkler-Mendez if he was ready to make the decision, Sierra replied, "It's been 14 years, so." When the judge asked for his plea, he responded, "I'm guilty."

Prosecutors say Sierra confessed to detectives in 2012. According to investigators, Sierra stabbed his wife, Gladys Machado, inside her car before driving her and her two daughters — 8-year-old Julia and 4-year-old Daniela Padron — to their home, where he suffocated them. DNA evidence found on Julia linked the stepfather to the crime, officials said.

A third child, who was 6 at the time, was left at home with his grandmother when the kidnapping occurred.

Sierra's fate will be decided by a jury later this month. The death penalty phase of the trial is scheduled to begin Aug. 17, at which point the jury will determine if Sierra will face the death penalty or life in prison without the possibility of parole.