The top Democratic candidate in this year's Senate race in Massachusetts was listed as a minority professor in a newly discovered University of Pennsylvania report â€" raising eyebrows a second time over how she and her employers characterized her heritage.

The scrutiny started last month after newspaper reports surfaced that Elizabeth Warren had listed herself in law school directories as having American Indian heritage. The latest revelation raises further questions about how Warren might have used such classifications to her professional advantage.

The 62-year-old Warren is attempting to unseat first-term GOP Sen. Scott Brown who has called on her to release all law school applications and personnel files from the universities where she taught.

A Massachusetts genealogist said he uncovered evidence that Warren's great-great-great grandmother had listed herself as Cherokee in an 1894 document. That would make Warren  1/32nd American Indian.

Requirements for tribal membership vary from tribe to tribe. The United Keetoowah Band of Cherokee Indians requires a bloodline of at least 1/4 Cherokee, according to the genealogy website All Things Cherokee. The Eastern Band of Cherokee Indians requires at least 1/16, making someone with a bloodline of 1/32 one generation beyond that threshold.

The race between Brown and Warren is among the mostly closely watched this year. The non-partisan Cook Political Report and leading polls list it as a tossup.

The high-stakes race could help decide whether Republicans take control of the Senate. But the candidates have agreed to a so-called “people's pledge” that has stopped millions of dollars in third-party ads from influencing the race.

The University of Pennsylvania document was one of three similar ones made public Thursday.

The second shows Warren identified herself as "white" on a University of Texas employment record, and the other indicates she declined to apply to Rutgers Law School under minority status.

Warren worked at the University of Texas from 1983 to 1987, before taking a job at the University of Pennsylvania Law School.

The University of Pennsylvania document -- a report published in 2005, 10 year after Warren left to teach at Harvard Law school â€" indicates she was a minority faculty member and had won a teaching award. The report stated only eight of the 112 awards give out during a 13-year span had gone to minority teachers.

Warren's campaign said the records from Rutgers and Texas bolster her argument that she was able to land a job at Harvard Law School in 1995 based on hard work and achievement, not claims of Native American heritage.

"At every law school where Elizabeth was recruited to teach, it has been made absolutely clear she was hired based on merit; on her accomplishments and ability," Warren spokeswoman Alethea Harney said in a statement Thursday.

Harvard Law School professor Charles Fried has said any suggestion that Warren enjoyed an affirmative-action advantage in her hiring as a full professor is "false" and that Warren was recruited because of her expertise in bankruptcy and commercial law.

The Associated Press contributed to this report.