U.S. Senator Lisa Murkowski has called for a formal inquiry within the Department of Justice to answer, publicly, why federal prosecutors blocked potential child sex abuse charges against former Veco CEO Bill Allen.

Murkowski says she can't just accept statements by Attorney General Eric Holder that there was no deal allowing Allen to avoid prosecution on those charges, in exchange for testimony in the public corruption trials of Alaska politicians.

The Department of Justice in Washington, D.C., is declining to respond to Murkowski.

But in a letter to the agency's acting inspector general and the office of professional responsibility, she says that DOJ must offer an explanation of why it did not prosecute Allen for transporting a minor prostitute across state lines -- and why it did not allow the Alaska Department of Law to do so, either.

It's a fight Murkowski has taken on before -- to find out why a potential child sex abuse case was not pursued.

Alaska’s senior senator challenged the U.S. attorney general in March on the lack of prosecution of Bill Allen, the government's key witness in the public corruption probe against the late U.S. Senator Ted Stevens and former Alaska legislators.

"We take into consideration, a number of factors, among them being the age of the case, the reliability of the witnesses, the ability to say that we have a better than 50 percent chance of winning a case,” Holder said.

Since learning that the Alaska Department of Law was denied permission to prosecute Allen on a federal charge of transporting a juvenile prostitute across state lines, Murkowski has ramped up the pressure -- asking for a formal inquiry into the internal decision-making by the Department of Justice -- which she wants made public.

Murkowski was reluctant this afternoon to suggest the possibility that Attorney General Eric Holder perjured himself on the Allen matter when testifying before the Senate.

"What we're learning about after the fact causes us all a great deal of concern. And in fact the attorney general of the United States was involved in helping to make a deal, so to speak, in exchange for some testimony, I think that we deserve to know about that."

But Cliff Groh, a former prosecutor who has blogged about the public corruption probe for years, says the outrage over Bill Allen is in part an attempt to rewrite history by denying the culpability of others.

"And there does seem to be a sentiment to want to wipe Alaska clean by putting all the blame on Bill Allen -- unique pervert, deviate, demon. I just don't think that works."

He also has a question for Murkowski regarding Stevens' son, Ben, former president of the state Senate.

"When did Lisa Murkowski ever ask the united states government and the united states department of justice in particular to explain why it didn't prosecute Ben Stevens after getting two witnesses to plead guilty to bribing him?"

Murkowski responded: "It's not something that I have thought to press. If you'll recall the timeline here, that investigation against Ben Stevens has been ongoing for quite a period of time. No information really revealed on that."

Justice has at least delayed in explaining prosecutorial decisions.

So the question persists, is that justice denied?

The matter also could get more scrutiny when federal Judge Emmett Sullivan decides which parts to release publicly from a 500-page special counsel's report on the prosecutorial misconduct in the Ted Stevens case.