In two separate letters sent on Tuesday, Senate Democrats — including pro-Israel stalwart Sen. Bob Menendez (D-NJ) — criticized as insufficient the Biden administration’s handling of the investigation into the killing of Palestinian-American journalist Shireen Abu Akleh.

In the first letter, Menendez and Sen. Cory Booker (D-NJ) told President Joe Biden it is “troubling” that the administration has failed to provide any details of the investigation to Abu Akleh’s family, requested a classified briefing and backed U.S. involvement in any further investigative efforts.

In the second letter, a forceful communique to Secretary of State Tony Blinken, Sens. Chris Van Hollen (D-MD), Patrick Leahy (D-VT), Chris Murphy (D-CT) and Dick Durbin (D-IL) slammed the U.S.’s forensic analysis of the bullet that killed Abu Akleh as insufficient, and pressed the administration for further details on the investigation.

The U.S. Security Coordinator (USSC) for Israel and the Palestinian Authority conducted a forensic analysis of the bullet that killed Abu Akleh during an Israeli Defense Forces raid on the West Bank city of Jenin. In a brief statement on July 4, State Department spokesperson Ned Price said the USSC “could not reach a definitive conclusion” because of damage to the bullet, but said that “gunfire from IDF positions was likely responsible” but that the shooting was likely unintentional.

In their letter, Menendez and Booker criticize the administration for failing to provide “any details of a ‘thorough…credible investigation’” to Abu Akleh’s family, some of whom are New Jersey residents, the letter notes. Abu Akleh was also a New Jersey resident, according to the letter.

The two New Jersey senators pressed Biden to “raise Ms. Abu Akleh’s case at the highest levels and press for accountability” during his upcoming visit to the Middle East, and urged U.S. participation in any ongoing investigations.

The letter goes on to request a high-level classified briefing on the state of the investigation, including the USSC’s involvement with the IDF and Palestinian Authority investigations, the bullet investigation and “next steps with the IDF and PA regarding accountability.”

Menendez and Booker added that “we must be clear to those individuals who attacked mourners during Ms. Abu Akleh’s funeral procession that this behavior is unacceptable,” an apparent reference to Israeli police who attacked members of the funeral procession. Israeli police have claimed that they were responding to attacks from the crowd and that the procession went against the wishes of Abu Akleh’s family.

“Ms. Abu Akleh’s courageous and unbiased reporting provided critical news not only for Palestinians and Israelis, but for the international community as a whole,” Menendez and Booker wrote. “We trust that you will treat this request for a classified briefing with the utmost urgency. We appreciate your personal consideration of this matter.”

Van Hollen and his co-signatories argued in their letter that the administration failed to live up to Blinken’s call for an “independent, credible investigation” into Abu Akleh’s killing.

The forensic analysis fails to meet “any plausible definition of the ‘independent’ investigation that you and members of Congress have called for,” the lawmakers wrote to Blinken. “Nor does it provide the transparency that this case demands.”

The lawmakers requested the full work product and analysis of the USSC from its investigation, as well as more than a dozen specific details about the investigation. They specifically questioned what led the USSC to conclude that IDF gunfire likely killed Abu Akleh and how the USSC determined that the shooting was unintentional.

They also asked whether the USSC determined that an IDF rifle identified by the IDF had been responsible for the killing, whether the soldier using that rifle had been questioned by the IDF and whether any U.S. agency requested to question said soldier.

“What steps will you take to ensure the ‘independent, credible’ investigation you called for?” the letter continues, further asking, “What steps do you plan to take to ensure… accountability?”

The letter concludes with a demand that Blinken “provide the requested materials and responses to these questions within two weeks” — an uncommonly direct request from a public letter to the administration.

AIPAC, which had opposed a previous Senate call for a U.S.-led investigation of the killing, did not directly respond to the two new Senate letters, but expressed opposition to any continued U.S. involvement in the case.

“While the U.S.-initiated review of this incident is rightly complete, we support the administration’s call for continued Israeli-Palestinian cooperation on this case,” AIPAC spokesperson Marshall Wittman said in a statement.

Menendez is a close longtime ally of the pro-Israel advocacy group.

Nineteen House lawmakers also proposed an amendment to the National Defense Authorization Act under consideration this week that would require the FBI, State Department, Director of National Intelligence and Defense Department to submit a report to Congress on Abu Akleh’s killing.