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The Fermilab HyperCP experiment has accumulated the world's largest sample of Ξ - and Ξ + hyperon decays within two running periods in 1997 and 1999. The primary goal of the experiment is to search for direct CP violation in the decay sequences Ξ - -> Λ π - -> p π - π - and Ξ + -> Λ π + -> p π + π + . A violation of CP would manifest itself as a difference between the angular distribution of the proton and the antiproton in the Λ and Λ helicity frame. The amount of data is enough to reach a statistical sensitivity of 1.4 x 10 -4 in the CP violating asymmetry A ΞΛ = (α Ξ α Λ - α Ξ α Λ )/(α Ξ α Λ + α Ξ α Λ ). We present an analysis method used to take into account the slight differences in the production of the Ξ - and Ξ + samples. A preliminary results on A ΞΛ at the level of a few 10 -3 and based on a few percent of the 1997 data will be presented.