In Resident evil Apocalypse, why did Umbrella make Nemesis kill all S.T.A.R.S members?

Because that movie is based off of resident evil 3 Nemesis in that game you play as Jill Valentine who is a S.T.A.R.S member and she and her copanion carlos are hunted down raccon city by Nemesis he tries too kill Jill becasue she is S.T.A.R.S