Each of the Blues' starting line-ups before facing Paris Saint-Germain over two legs in the Champions League were leaked hours before kick-off.
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After this week's defeat at Stamford Bridge, Rosenior said an investigation would be held to uncover the culprit.
On Thursday, ahead of Chelsea's clash with Everton, Rosenior declared: "We know (who it was).
"It's not come from any place of malicious intent to me or the team. We've dealt with the situation."
Chelsea go to Everton on Saturday sitting in sixth place on the Premier League table, three points outside the top four.