She appeared on the cover of Seventeen magazine, which caught the attention of television producers who were casting for the comedy My Sister Sam starring Pam Dawber.

[11] Schaeffer won the role of Patricia "Patti" Russell, a teenager who moves from Oregon to San Francisco to live with her 29-year-old sister Samantha ("Sam") after the death of their parents.

[7][13] My Sister Sam was initially a hit, ranking in the top 25, but it was canceled halfway through its second season in April 1988 due to falling ratings.

[4] After My Sister Sam, Schaeffer had supporting roles in Scenes from the Class Struggle in Beverly Hills, Voyage of Terror: The Achille Lauro Affair,[6] The End of Innocence, and the television film Out of Time.

He returned to his native Tucson, Arizona, and lost focus on Schaeffer for a while as his obsession shifted toward pop singers Tiffany, Debbie Gibson, and Madonna.

[17] Bardo watched Schaeffer in the black comedy film, Scenes from the Class Struggle in Beverly Hills in 1989, in which she appeared in bed with another actor.

[6] Bardo then paid a detective agency in Tucson $250 to find Schaeffer's home address in California's Department of Motor Vehicles (DMV) records.

[15] He pulled out the handgun and shot her in the chest at point-blank range in the doorway of her apartment building; according to Bardo, she said "Ouch" and fell and said only, "Why?

[28] Tucson Police Chief Peter Ronstadt arrested Bardo the next day after motorists reported a man running through traffic on Interstate 10.

[31][32] Schaeffer's death also helped prompt the 1990 passing of America's first anti-stalking laws, including California Penal Code 646.9.

Shortly after Schaeffer's death, Pam Dawber and her My Sister Sam co-stars Joel Brooks, David Naughton, and Jenny O'Hara filmed a public service announcement for the Center to Prevent Handgun Violence in her honor.