On October 30, 1982, Dunne was strangled by her ex-boyfriend John Sweeney during an argument on the driveway of her West Hollywood home.

[8] She studied acting at Milton Katselas' Workshop and appeared in various stage productions, including West Side Story, The Mousetrap, and My Three Angels.

After her television appearances, in 1981, Dunne was cast in the supernatural horror film Poltergeist in the main role of Dana Freeling,[9] the teenaged daughter of a couple whose family is terrorized by malevolent ghosts.

[15] She was set to reprise the role in the following installments of the franchise, but she died before production began on the sequels; Poltergeist II: The Other Side,[16] filmed in 1985 and released in 1986,[16] explains her character's absence by stating that she has gone off to attend college.

[17] Her last on-screen appearance was in the Hill Street Blues episode "Requiem For a Hairbag", which aired on November 18, 1982, only two weeks after her death.

[18] Dunne was cast in the miniseries V in 1982; she died during filming, so her role was portrayed by actress Blair Tefkin.

[21] Dunne met John Thomas Sweeney, a sous-chef at the restaurant Ma Maison, at a party in 1981.

After a few weeks of dating, they moved into a one-bedroom house together on Rangely Avenue in West Hollywood.