A New Jersey congressman wrote directly to Defense Secretary Leon E. Panetta two months ago to seek details about the Dover Air Force Base mortuary’s practice of dumping troops’ cremated body parts in a landfill but says he never received a reply.

The congressman’s letter raises questions about when Panetta learned that the mortuary disposed of cremated portions of remains at the King George County, Va., landfill. Panetta has said he was unaware of the dumping before this week.

Rep. Rush Holt (D-N.J.), acting on behalf of a constituent whose husband was killed in Iraq and was prepared for burial by the Dover mortuary, said he sent a letter to Panetta on Sept. 16 “seeking clear and definitive answers” about the mortuary’s landfill practices. Holt said he had raised the issue a few months earlier with the Pentagon’s legislative affairs office but was “frustrated by a failure” to get a full response.

Pentagon press secretary George Little said Friday that Panetta’s office had received Holt’s Sept. 16 correspondence and that staffers “have been working to collect the information required to answer the questions in the congressman’s letter. We will, of course, provide a thorough response as promptly as possible.”

Little said Panetta was first briefed on the issue Wednesday.

At a news conference Thursday, Panetta said he had been kept informed about a broader federal investigation into problems at the Dover mortuary but had been unaware of the landfill arrangements until The Washington Post reported on them the day before.

“I did not know that, frankly,” he said.

“I think that it happened back in the past,” added Panetta, who took office July 1. “I know they’ve changed that procedure now, but nevertheless it’s something we should look at.”

The Dover mortuary handles the remains of American troops killed overseas. The Air Force said that it ended the landfill dumping in 2008 and that the ashes are now buried at sea in ceremonies overseen by the Navy.

Air Force officials have said they dumped only cremated fragments or portions of body parts that were unable to be identified at first or were later recovered from the battlefield. Family members had authorized the military to dispose of those portions.

The Air Force said the body parts were cremated, then incinerated, and taken to the landfill by a military contractor. The manner of disposal was not disclosed to relatives of the troops.

In his letter to Panetta, Holt asked why the ashes were trucked to the landfill and not interred at Arlington National Cemetery. He also asked whether the human remains had been mixed with incinerated medical waste, and he sought information on which military contractors were responsible.

As of Friday, Holt said, he still had not received answers from Panetta’s office.

“I thought there would be some straightforward explanation that we could get fairly quickly,” Holt said in a telephone interview. “Evidently this has been harder for them to answer.”

Holt said he was acting on behalf of Gari-Lynn Smith, a constituent whose husband, Army Sgt. 1st Class Scott R. Smith, was killed by a buried bomb in Iraq in 2006.

In 2007, Gari-Lynn Smith received her husband’s autopsy report and learned that some remains had not been found in time to include in his casket.

Over the next four years, she tried to find out what happened to those body parts. A Dover mortuary official notified her in April that they had been cremated and taken to the landfill.

Holt said the Pentagon’s legislative affairs staff confirmed to him in June that the landfill dumping had taken place between 2003 and 2008. Though they did not give details, they wrote to Holt that the practice ended as part of “a process improvement initiative and not the result of complaints or findings of non-compliance.”

In a statement, Holt disputed that assertion.

“It is now clear to me that real issues did and may still exist, complaints were made and non-compliance was an all too common occurrence at Dover,” he said.

In addition, Holt criticized the Pentagon for not informing him — at the time of his inquiries this summer — that the Air Force was simultaneously conducting a separate investigation into the Dover mortuary.

The results of that 18-month investigation were made public Tuesday, when federal investigators said they had documented “gross mismanagement” after whistleblowers complained about lost body parts, shoddy inventory controls and lax supervision.

Panetta has said he was fully briefed about the probe as soon as he took office in July. That investigation, however, did not examine the mortuary’s landfill-dumping.

The defense secretary appointed an independent panel Tuesday to review overall operations at the mortuary. The panel’s leader, former U.S. surgeon general Richard H. Carmona, quit Friday so he instead could run for the Senate. He is seeking an open seat from Arizona.

The Pentagon said Panetta would name a replacement to head the review panel.