She was born Jeanne-Paule-Marie Deckers on October 17, 1933 and in September 1959 entered the Missionary Dominican Sisters of Our Lady of Fichermont, headquartered in the city of Waterloo, who had been founded to provide assistance to the Dominican friars in their missions in the Belgian Congo. While in the convent, she wrote, sang and performed her own songs, which were so well received by her fellow Sisters and by visitors, that her religious superiors decided to let her record an album, which visitors and retreatants at the convent would be able to purchase.
In 1963, the album was recorded in Brussels at Philips. The single "Dominique" became an international hit. Many radio stations in the U.S. played it and other softer hits more often in the wake of the John F. Kennedy assassination. Overnight, the Dominican Sister was an international celebrity, with the stage name of Sœur Sourire (Sister Smile). "Dominique" was the first Belgian song to be a number one hit single in the United States. In 1966, a movie called The Singing Nun was made about her, starring Debbie Reynolds in the title role. Deckers rejected the film as "fiction". My grandfather loved that corny film, and for a long time it was hard to find on video.
Deckers did not gain much from this international fame, and her second album, Her Joys, Her Songs, did not get much attention and disappeared almost as soon as it was released. Most of her earnings were in fact taken away by Philips, her producer, while the rest automatically went to her religious congregation. She left the convent in 1967, planning to continue her musical career under the name Luc Dominique and to pursue social work, which she had studied at the Louvain, becoming a lay Dominican. She moved in with a childhood friend, Anne Pecher, a physiotherapist who was also a former member of the Dominican Sisters. She could not keep her initial professional name of Sœur Sourire, as the Dominican Sisters owned the rights and refused permission.
Deckers released an album entitled I Am Not a Star in Heaven. Her repertoire consisted of religious songs and songs for children. Despite her renewed musical emphasis, Deckers gradually faded into obscurity, possibly because of her own disdain for fame. She was never able to duplicate the success of her one hit.
Her musical career over, Deckers opened a school for autistic children. In the late 1970s, the Belgian government claimed that she owed $63,000 (approximately the equivalent of some $275,000 as of 2012) in back taxes. Deckers countered that the royalties from her recording were given to the convent and therefore she was not liable for payment of any personal income taxes. As her former congregation refused to take any responsibility for the debt, claiming both that they no longer had any responsibility for her and that they did not have the funds, Deckers ran into heavy financial problems. In 1982, she tried, once again as Sœur Sourire, to score a hit with a disco synthesizer version of "Dominique", but this last attempt to resume her singing career failed.
The song - and the singer - turned out to be a bit of a one-day wonder. By the 1980s, she had many problems - with money, with the Roman Catholic Church, and with her own sexuality. On March 29,1985 , she and her longtime companion, Anna Peche, had a few drinks, a bunch of barbituates, and died. The double suicide made headlines at the time, but today, very few people remember either The Singing Nun, or the song that made her famous.
Despite the fact that they had committed suicide, she and Pécher were granted their request for a church funeral. They were buried together in Cheremont Cemetery in Wavre, Walloon Brabant, the town where they died. The inscription on their tombstone reads "I saw her soul fly across the clouds", a line from Decker's song "Sister Smile is dead"...