The Los Angeles County District Attorney's Office is apologizing to the Menendez family for not giving advanced warning that crime scene photos would be shown at a recent hearing ... but, they add the choice was made to show the full truth.

In a statement to TMZ ... the L.A. County D.A.'s Office tells us they apologize for the upsetting nature of the crime scene photos they showed -- adding it wasn't the office's intention to upset the members of the family.

However, we're told these hearings are "intended to be a place where the truth, no matter how painful, is brought to light" ... so, the photos needed to be shown in order to depict the brutality of the crime.

The D.A.'s office puts part of the blame on Erik and Lyle's request for clemency ... explaining that the motion was always certain to "trigger emotions for all those concerned in a case that had lied dormant legally for over 18 years."

The office notes that motions filed by prosecutors have often described the killings of Jose and Kitty Menendez ... including how the two brothers killed their parents with 13 shots fired from a shotgun from close range and other grisly details.

Either way, the L.A. County D.A's office continues, "To the extent that the photographic depiction of this conduct upset any of the Menendez family members present in court, we apologize for not giving prior warning that the conduct would be described in detail not only in words but also through a crime scene photo."

The L.A. County D.A.'s Office also defends the conduct of District Attorney Nathan Hochman ... pointing out he met with more than two dozen family members of Erik and Lyle for more than three hours -- something they claim no prior D.A. has done for the family in more than three decades.

The statement ends with a blanket trigger warning ... telling people who are coming to the hearing to "be prepared for some of the difficult details and images surrounding these tragic circumstances."

The statement does not include a response to the allegation that showing the crime scene photos during Friday's resentencing hearing sent Terry Baralt to the hospital.

As we told you ... the 85-year-old aunt of Erik and Lyle was found unresponsive in her hotel room this weekend -- and, the family says she's in critical condition because of the stress around this trial, particularly regarding the gruseome photos.

Bryan Freedman -- the attorney representing the family -- slammed prosecutors for showing these images ... calling the move a "despicable action [that] was a clear violation of Marsy’s law which requires absolute empathy toward victims."

Mark Geragos -- Erik and Lyle's attorney who cohosts our "2 Angry Men" podcast -- made similar statements during a news conference Friday after a judge granted Erik and Lyle a resentencing hearing next week.