<P> The mystery surrounding Mary Alice and her family was the main storyline in the first season of the series, and it is resolved in the first season finale . Cherry had wanted there to be a "definite end" to the mystery, hoping to avoid similar viewer fatigue that Twin Peaks suffered after drawing out its central mystery past its first season . ABC executives initially protested the writers' decision to have Mary Alice purposefully kill Deirdre Taylor (Jolie Jenkins), the woman whose child she had illegally purchased, prompting the writers to make Deirdre violent in order to justify Mary Alice's actions . Although Mary Alice and her family do not have much of a leading storyline thereafter, the mystery surrounding the character's suicide in the inaugural season is said to have informed and influenced every other season of the series . In 2006, when asked during an interview what viewers could expect from Mary Alice for the series' third season, Strong said that the character was "going to be back with an attitude", stating: "She will be a little less surreal, ethereal and a little more sassy, which means the show is going to be sassier ." During the series' final season in 2011, the actress appears as Mary Alice's ghost to her suicidal friend Bree (Marcia Cross). Strong enjoyed filming that particular scene, as it was the only scene during the entire series that featured solely Mary Alice and Bree . She described the scene as one of her personal favorites and called it an "extraordinary opportunity", saying: "In a way, Mary Alice becomes (Bree's) conscious and her guide and her muse in knowing what to do with her life . And it was an exquisitely written scene and it was really, I think in my experience on the show, one of my favorite scenes I have ever shot ." </P> <P> In the pilot episode, Mary Alice introduces herself as the stereotypical American housewife to husband Paul Young (Mark Moses) and son Zach (Cody Kasch). On one Thursday, she proceeds to go to her hall closet to retrieve a revolver, and shoot herself in the head with it . </P> <P> Paul asks Mary Alice's neighbors and friends, Susan (Teri Hatcher), Lynette (Felicity Huffman), Bree (Marcia Cross) and Gabrielle (Eva Longoria), to go through her clothes and other belongings and then pack them up, as he thinks it will be too hard for him . The women end up finding a letter addressed to Mary Alice, a blackmail note reading, "I know what you did, it makes me sick, I'm going to tell ." Thereafter, the women make a series of discoveries concerning Mary Alice's past and her possible motives for ending her life; she was being treated by Dr. Albert Goldfine (Sam Lloyd) where she revealed that she once went by the name Angela, and she may have had something to do with a baby that went missing . Paul soon discovers who sent Mary Alice the note, their next - door neighbor struggling with financial difficulty, Martha Huber (Christine Estabrook), whom he ends up strangling to death out of pure rage and burying her body in the nearby forest . Meanwhile, her son Zach begins having flashbacks and is under the impression he killed a baby named Dana, who he believed to be his younger sister and reveals this to Julie Mayer (Andrea Bowen), Susan's daughter . Paul worries over what Susan is spreading about their family, so he tells Susan in private that Zach accidentally killed his younger sister, Dana, and that he and Mary Alice covered it up to protect him . However, it becomes evident that this is not the case when Paul tells Zach that Dana is still very much alive . </P> <P> Felicia Tilman (Harriet Sansom Harris), Martha's sister, soon arrives on Wisteria Lane to find out what happened to her sister . While inside Paul and Mary Alice's house, she recognizes a picture of Mary Alice and claims her to be Angela, a nurse she worked with years prior in Utah, but Paul is adamant that she is mistaken . Felicia, however, knows that Mary Alice was in fact Angela and later tells Zach that she knew him when he was a baby, and that his original name was so lovely: Dana . In the first season finale, the mystery behind Mary Alice's suicide is revealed in full . In March 1990, Todd and Angela Forrest could not conceive and one night a woman named Deirdre Taylor (Jolie Jenkins), a heroin addict whom Angela had treated at the rehabilitation hospital where she worked as a nurse, came to their house looking for money and offered to sell her son to them, to which they eventually agreed . When Deirdre returned to the hospital as a patient soon after and suspicion arose as to where her child was, Angela knew they had to leave town . They moved to Fairview and bought a house on Wisteria Lane, changing their names to Paul, Mary Alice and Zach Young . In 1993, however, Deirdre came to their home, seemingly sober, demanding that she reclaim her son . After a verbal fight, Deirdre went to take her child, when Mary Alice stabbed and killed her . Zach woke up and saw the body, which led to years of his parents brushing off his memories of that night as nothing . Paul and Mary Alice dismembered Deirdre's body, put it in a toy chest and buried it under their pool . Years later, Martha recognized Mary Alice in a group photo in Felicia's house, leading to Felicia to tell Martha about how Angela and Todd possibly disappeared with Deirdre's child and hopefully gave Dana a proper home . Martha then blackmailed Mary Alice and she, in desperation, committed suicide . </P>

Who wrote the letter to mary alice in desperate housewives