MADISON, Wis. (AP) — A University of Wisconsin physician and her husband whose bodies were found at the school’s arboretum near the Madison campus were shot to death, and a second teenage suspect in the killings has been arrested, police said.

Police said Saturday that they arrested Ali’jah Larrue, 18, on Friday night. Larrue was booked into jail on two counts of party to the crime of first-degree intentional homicide.

UWpolice spokesman Marc Lovicott said Sunday that Larrue is an acquaintance of the other suspect, Khari Sanford, 18, who was arrested earlier Friday and booked on the same charges.

“We are confident these are the two guys,” Lovicott told The Associated Press, although the investigation remained active.

A jogger found the bodies of Dr. Beth Potter, 52, and her husband, Robin Carre, 57, last Tuesday, in a ditch at the university’s arboretum, a research and popular recreational area.

Lovicott said the couple had been shot at the arboretum sometime overnight before their bodies were found, but that police were not ready to discuss a motive.

Police have said the couple was targeted and that Sanford was known to the victims’ family.

The suspects have not been formally charged but are expected to make their initial court appearances early this week, Lovicott said. He did not know if they have attorneys who could speak on their behalf.