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The Philadelphia district attorney is speaking out against President Obama's nominee for a top Justice Department post, saying his link to the case of a convicted cop killer "sends a message of contempt" to police -- as the widow of the fallen officer is apparently denied the chance to testify.

Maureen Faulkner, whose husband Daniel Faulkner was killed in 1981, was hoping to speak publicly on the case before the Senate Judiciary Committee, which plans to vote Thursday on the nomination of Debo Adegbile to lead the Civil Rights Division.

But she told FoxNews.com she's "extremely frustrated" after being told by representatives of Judiciary Committee Chairman Patrick Leahy, D-Vt., that she won't be able to do so.

"I am physically, emotionally and mentally distressed that I'm not able to be in that room," Faulkner told FoxNews.com by phone. "This is personal to me."

Faulkner said she received a letter from Leahy's office this week informing her that it's "not the practice" of the committee to accept outside testimony. Faulkner, who lives in Los Angeles, later realized she could attend the hearing as a member of the public but was unable to book a flight.

"I couldn't sleep all night," she said. "If I found out about this before yesterday and I could physically be there, I would be there."

A Leahy spokeswoman told FoxNews.com that a hearing to consider Adegbile's nomination was already held on Jan. 8, and lawmakers were allowed to ask questions on his background then. She reiterated that "it's not the practice" of the committee to have outside witnesses.

Faulkner, in seeking to testify, claimed Adegbile "personally took on" the case of Mumia Abu-Jamal while working with the NAACP to overturn Abu-Jamal's death penalty. Abu-Jamal was convicted in the 1981 killing of Daniel Faulkner.

The nominee has faced criticism for his role in getting Abu-Jamal's death sentence overturned during his time as acting director of the NAACP Legal Defense and Educational Fund.

Adegbile, 46, told the Senate committee last month that he had no direct role in three briefs submitted on behalf of Abu-Jamal by the NAACP, though he did lead the unit that sent them. The briefs pertained to concerns about the death sentence rather than the guilt of Abu-Jamal. Abu-Jamal was initially sentenced to death, but that penalty has been overturned. Now 59, Abu-Jamal remains imprisoned in Pennsylvania.

Philadelphia District Attorney Seth Williams, a Democrat, said Adegbile is "ill-suited for the pivotal role" of leading the Civil Rights Division. He voiced his concerns in a Feb. 4 letter to Leahy and Ranking Member Chuck Grassley, R-Iowa.

"Mr. Adegbile has impressive credentials," Williams wrote. "His decision to champion the cause of an extremist cop-killer, however, sends a message of contempt to police officers who risk their lives every day to maintain the peace."

Adegbile's connection to Abu-Jamal and Obama's decision to nominate him to head a key post within the Justice Department has outraged Faulkner's widow. "This man voluntarily took on this case to try and get [Abu-Jamal] off of death row and probably out of prison," she said. "Where are my civil rights?"

If Adegbile is confirmed, Faulkner said she'd feel as if the Justice Department "failed" her for a second time.

Adegbile has served as the committee's senior counsel since last year. Adegbile, for his part, told the Senate committee last month that his role in Abu-Jamal's legal representation does not negate the "grievous loss" of the late Philadelphia cop.

"It's important, I think, to understand that in no way does that legal representation, zealously as an advocate, cast any aspersion or look past the grievous loss of Sergeant Faulkner," Adegbile said.

Sen. Pat Toomey, R-Pa., also opposes Adegbile's nomination, saying his record raises "serious questions" about his judgment.

"Notably, a team of defense lawyers managed by Mr. Adegbile distorted the facts in the case for Mumia Abu-Jamal, the unrepentant murderer who took the life of Philadelphia Police Officer Daniel Faulkner 32 years ago," Toomey said in a statement to FoxNews.com.

Williams, meanwhile, noted in his letter to Leahy and Grassley that Abu-Jamal made every effort to turn his trial into "political theater" by repeatedly interrupting the proceedings and insulting the judge.

"Of course, in our system even a radical cop-killer Mumia Abu-Jamal is entitled to legal representation," his letter continued. "That does not mean, however, that those lawyers who elect to arm him in his efforts are suitable to lead this nation's highest law enforcement offices."

Those who know Adegbile personally, however, say he's the best man for the job. One such supporter is Terrance Daniels, a retired detective from the New York City Police Department. In a letter to the Senate committee, Daniels, who has known Adegbile as a classmate, co-worker and friend throughout three decades, said Obama's pick has "always been known" for having the highest integrity and character.

"He has always displayed a work ethic that would be hard to duplicate," Daniels wrote. "His knowledge of individual's legal rights will be perfectly used in the position he has been nominated for. He will protect everyone's civil rights with an enthusiasm and knowledge that will be second to none."