The Michigan man accused of murdering 13-year-old Adrie Dembowski in June was recently also charged with killing a Lansing couple in April.
Authorities allege Gardenhire killed Harley Owens, 39, and his 29-year-old girlfriend, Kelsey Coon-Lennon, on April 28.
Owens and Coon-Lennon were shot to death. Their bodies were found May 1.
A motive for the killings is not known at this time.
Jessica Rutz, Owens’ sister, told the State Journal her brother was very handy.
“He was a pretty handsome fella, but very quiet,” Rutz said. “Girls kind of flocked to him… He had a great sense of humor.”
Coon-Lennon had a good heart and always wanted to make others smile, Michelle Bott, one of her friends, told the paper.
Gardenhire was already facing a dozen felony charges stemming from an alleged 45-hour crime spree that unfolded in June and included robberies and carjackings along with Dembowski’s killing, as well as the sexual assaults of two different women.
According to Michigan State Police, Dembowski was stabbed to death at a residence in Union Township on June 6. Prior to killing Dembowski, Gardenhire is accused of sexually assaulting another woman.
An online obituary for the teen said she was “a happy-go-lucky and sweet girl” who “loved everything about life and brought much joy to everyone around her.”
For two days after the girl’s killing, police say Gardenhire hid from police for hours in a vacant apartment. Authorities allege he emerged several hours later and approached a man and woman.
Police allege he struck the man, and entered the couple’s apartment, holding them both hostage. According to officials, Gardenhire then repeatedly sexually assaulted the female before stealing money from the couple and fleeing in their 2014 Ford Fusion.
In June, Gardenhire was arraigned on single counts of open murder, armed robbery, carjacking, first-degree home invasion and first-degree criminal sexual conduct using a weapon, as well as three counts of first-degree criminal sexual conduct with multiple variables and two counts each of unlawful imprisonment and assault with a dangerous weapon.
Not guilty pleas had been entered on his behalf by the court. PEOPLE could not reach his public defender for comment.
It was unclear Thursday if he had entered pleas to the two new murder counts he faces.