PHILADELPHIA (CBS) — A series of racist text messages were sent to black freshmen at the University of Pennsylvania last week. The source of the texts were traced back to a student at the University of Oklahoma.

The text messages referenced lynching and included racial slurs. They managed to find their way to black freshmen students at Penn using the app GroupMe.

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On Tuesday night, Penn sought to answer the question of how someone at the University of Oklahoma, was able to contact a number of students from the University of Pennsylvania. In a tweet, Penn explained that the person believed to be responsible was offered admission to Penn earlier this year.

Penn President Amy Gutmann explained in the statement that the investigation showed that Penn’s directory was not compromised, but that because the student was offered admission to Penn, and originally accepted, they were added to the Class of 2020 Facebook page.

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Gutmann explained that the access to the page, allowed the student to gain the contact information of the freshmen who received the messages.

Earlier on Tuesday, an Oklahoma student, that officials say was involved, was expelled from the school.