Salling was first arrested at his Los Angeles home in December 2015 after police and government agents seized a laptop, hard drive and flash drive that contained images and videos depicting child pornography.
On Tuesday morning Salling's attorney, Mark J. Proctor, confirmed the actor's death.
In his statement, Proctor said Salling is survived by his parents and brother. He also said that Mark's family asked for privacy in this time of mourning.
After a plea deal, he was expected to get a sentence of between four and seven years in prison.
Salling reached a plea agreement with prosecutors in October after admitting he possessed images of prepubescent children.
The sentencing was set for March 2018.
The 35-year-old Salling's next of kin have not yet been notified and his body remains at the scene while officials continue their investigation.
Salling reportedly made a previous suicide attempt in August 2017 by cutting his wrists, per TMZ, before being treated at a hospital and being taken elsewhere for psychiatric evaluation and treatment. He also agreed to pay $50,000 to each victim who submitted a formal restitution request, and to spend 20 years under supervised release.
This is a breaking news story and has been updated throughout.