Updated at 6:45 p.m. with comments from those at the sentencing.

ST. CHARLES COUNTY — Pamela Hupp was sentenced Monday to life in prison without parole for fatally shooting a mentally disabled man three years ago.

Prosecutors say Hupp tricked 33-year-old Louis Gumpenberger into entering her car, drove him back to her O'Fallon, Missouri, house, planted a knife and a kidnapping note, and shot him while she was on the phone with a 911 dispatcher.

“Hupp has done nothing but cause heartbreak and grief to so many families,” said Gumpenberger’s half-sister, Krystal Conn, calling Hupp a “monster,” “disgusting” and a “serial killer.”

Conn, wearing a pin with her brother's picture on it, remembered him for his corny laugh, love for his mother and devotion to his two children.

St. Charles County Circuit Court Judge Jon Cunningham noted that Hupp unsuccessfully tried to get two other people in her vehicle before finding Gumpenberger.

“He was an innocent person whose life did not deserve to be extinguished by you,” Cunningham said.