Sheridan's manager, Mitch Clem, told the outlets the actress died Monday in her home.
“We all loved Lisa very much and are devastated by the loss we all feel,” Clem said in a statement to People. “She passed away Monday morning, at home, in her apartment in New Orleans. We are waiting for a coroners report on cause of death.”
Clem said that everyone was "blindsided" by Sheridan's death in a statement to Deadline: “Obviously, we were all blindsided with this devastating loss. Lisa was deeply loved. We are heartbroken.”
Clem told People: “The family has unequivocally confirmed that this is not a suicide. Any suggestion to the contrary is absolutely, 100 percent unfounded.”
Sheridan's career spanned two decades and included acting credits on "Legacy," "Scandal," "Journeyman" and "NCIS."
Actress Donna D'Errico, who worked with Sheridan on the 2015 movie "Only God Can," wrote about her co-star's death in a Facebook post.
"I just received news that my dear friend, actress Lisa Sheridan, has passed away," D'Errico wrote. "I am sitting here stunned. Lisa and I filmed a movie together 5 years ago and became very close on set and remained close friends after filming ended."
She continued: "It’s so rare to find kind, gentle souls like hers in this industry, this city... even this world. Truly one of the most genuinely sweet and gentle people I’ve ever come across in my life."
D'Errico said Sheridan "brought a sweetness and bright energy to any room she happened to walk into...even in her darker times."
"I am devastated by this loss. I had just spoken with her and everything seemed great and she seemed happy and in good spirits," D'Errico said. "Everyone who knew her loved and adored her. Goodbye and goodnight sweet angel...I will miss you terribly."
This article originally appeared on USA TODAY: Lisa Sheridan, 'Halt and Catch Fire' star, dead at 44: reports