Heinz made her Olympic debut, as a 19-year-old, at the 2000 Summer Olympics in Sydney, competing in both 50 and 100-metre freestyle. First, Heinz touched out Thailand's Pilin Tachakittiranan to take the fourth spot in heat three of the women's 100 m freestyle by 0.14 of a second in 58.55. In her second event, 50 m freestyle, Heinz snared the fifth spot by two hundredths of a second ahead of Fiji's Caroline Pickering in 26.55, but fell short to advance to the semifinals, placing thirty-fourth overall on the morning prelims. Heinz also served as Luxembourg's flag bearer in the opening ceremony.