(CNN) Nikolas Cruz wants to plead guilty so that he can avoid the death penalty and spare a traumatized South Florida community a trial that would recount horrifying details of his mass shooting, a top public defender said Friday.

"This is an opportunity to put the criminal case behind and help the victims' families begin to try and pick up pieces of their lives for our community to heal and to figure out how we stop these things from ever happening again," said Broward County Public Defender Howard Finkelstein.

Prosecutors, who would need to agree not to ask for capital punishment -- by allowing life without parole, instead -- could not immediately be reached for comment.

Finkelstein, whose office is representing the confessed killer, said there is no question Cruz is guilty of killing 14 students and three staff members in Parkland on Wednesday.

"The only question is, does he live or does he die?" Finkelstein said.

Cruz is charged with 17 counts of premeditated murder.

The next court date is set for Monday morning, during which a judge will hear a defense motion unrelated to the possible plea.

Latest developments

• A person close to Cruz contacted the FBI on January 5 to report concerns about him, the bureau said.

• The school district has proposed tearing down the Marjory Stoneman Douglas High School building where the shooting happened, Parkland Mayor Christine Hunschofsky said.

• The President and the first lady visited several injured patients at a Florida hospital.

• Jim Gard, a math teacher at the school, says an administrator sent an email in late 2016 asking to be notified if Cruz came on campus with a backpack. The administrator gave no explanation for the email, Gard said.

• An initial investigation indicates Cruz fired nearly 150 shots from his rifle, according to a law enforcement source speaking on condition of anonymity.

• Cruz purchased the firearm used in the shooting, an AR-15-style weapon, legally in Florida nearly a year ago, according to Peter J. Forcelli, special agent in charge of the Miami division of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

• Cruz legally purchased at least five other guns in the past year, a law enforcement source briefed on the investigation said.

FBI did not pursue tip that came in

Families of the victims are lamenting what they say is inaction on gun control and school security. The anger comes as more signs emerged that authorities missed chances to intervene weeks beforehand.

The FBI has acknowledged receiving two tips that appear to relate to Cruz ahead of the shooting.

The caller provided information about "Cruz's gun ownership, desire to kill people, erratic behavior, and disturbing social media posts, as well as the potential of him conducting a school shooting."

The information should have been assessed as a "potential threat to life," but the proper protocols weren't followed and the Miami office was not notified, the agency said.

FBI Director Christopher Wray said the bureau is investigating what happened.

"We have spoken with victims and families, and deeply regret the additional pain this causes all those affected by this horrific tragedy," Wray said in the statement. "All of the men and women of the FBI are dedicated to keeping the American people safe, and are relentlessly committed to improving all that we do and how we do it."

YouTube user with the same name as Cruz. An FBI agent confirmed that a field officer in Jackson, Mississippi, received the tip and interviewed the person who shared it. Additionally, a video blogger said he warned the FBI in September about a possible school shooting threat from aYouTube user with the same name as Cruz. An FBI agent confirmed that a field officer in Jackson, Mississippi, received the tip and interviewed the person who shared it.

But no additional information was found to help identify the person who posted the comment and no connection was made to South Florida, said Robert Lasky, FBI special agent in charge of the Miami division.

Families demand action -- now

The FBI's announcement came as families prepared to bury their children.

Survivors and victims' relatives are directing their ire at state and national politicians, demanding action and venting frustration over allegations that the 19-year-old suspect expressed a desire to commit exactly the kind of massacre of which he's accused.

"President Trump, you say, 'What can you do?' You can stop the guns from getting into these children's hands! Put metal detectors at every entrance to the schools!" Lori Alhadeff , whose daughter Alyssa, 14, was killed at the school, told CNN. Alyssa, one of 14 students and three staff members killed, was buried Friday.

At a vigil in Parkland on Thursday evening, Fred Guttenberg, the father of one victim, spoke of his pain.

"I sent her to school yesterday," Guttenberg, his voice on the verge of breaking, said of his 14-year-old daughter Jaime. "She was supposed to be safe. My job is to protect my children and I sent my kid to school."

"What is unfathomable is that Jaime took a bullet and is dead," he paused, shaking his head. "I don't know what I do next. ... We are broken."

President praises emergency workers

Trump also visited the Broward County Sheriff's Office headquarters, where he met with first responders who played a role in rescues and the arrest of the shooter.

"What a great job you've done and we appreciate it very much," he said.

JUST WATCHED Student gives tearful tribute to slain teacher Replay More Videos ... MUST WATCH Student gives tearful tribute to slain teacher 01:25

Trump told reporters at Broward Health North hospital that he spoke to victims, adding that it is "very sad something like that could happen." The President heralded the efforts of the hospital staff and first responders to save lives.

Trump did not respond when asked whether more gun laws were needed to prevent school shootings.

Earlier, he pledged to hold a meeting with "the nation's governors and attorney generals where making our schools and our children safer will be our top priority."

I will be leaving for Florida today to meet with some of the bravest people on earth - but people whose lives have been totally shattered. Am also working with Congress on many fronts. — Donald J. Trump (@realDonaldTrump) February 16, 2018

Concerns about social media posts

Cruz's apparent digital footprint , which includes slurs against blacks and Muslims and declarations of wanting to shoot people, paint a disturbing picture. Posts under videos on YouTube and other sites by someone using the name Nikolas Cruz include threatening comments, such as:

"I whana shoot people with my AR-15."

"I wanna die Fighting killing s**t ton of people."

On an Instagram account under the name @Nikolascruzmakarov, the profile picture shows a person wearing a mask and a "Make America Great Again" hat. Other posts include a photo of a rifle, a collection of firearms on a bed, and a photo taken through a scope looking out a window.

Also, Jim Gard, a math teacher at the school, said an administrator sent an email out in late 2016 asking staff to notify him if Cruz came on campus with a backpack. The administrator gave no explanation for the email, Gard said.

Cruz was in Gard's class for only a couple of months and was never a problem, the teacher said.

'Significant mental illness'

Questions also are being raised about Cruz's home life and mental health.

Cruz's adoptive mother, Lynda Cruz, died in November of pneumonia, and his adoptive father passed away years ago, said Kathie Blaine, Lynda's cousin.

After Lynda Cruz's death, the family of someone Cruz met at the high school let him stay in their home, said Jim Lewis, the host family's attorney.

That family knew he had a gun, Lewis said. "They had it locked up, and believed that that was going to be sufficient, that there wasn't going to be a problem."

The family was unaware of any mental illness beyond depression over his adoptive mother's death, Lewis said.

"Obviously, he'd lost his mom. But they helped him get a job at a Dollar Tree store. They got him going to an adult education so he could try to get his GED and he seemed to be doing better," Lewis said.

But Gordon Weekes, executive chief assistant of Broward's public defender's office, said Thursday that Cruz is "suffering from significant mental illness and significant trauma."

Before Lynda Cruz died, Broward sheriff's deputies were called to the Cruz family home 39 times since 2010, according to documents obtained by CNN.

The sheriff's office received a range of emergency calls that included reports of a mentally ill person, child/elderly abuse, a domestic disturbance and a missing person.

Broward County Sheriff Scott Israel said Friday there were 20 calls for service over the past "few years" pertaining to Nikolas Cruz.

Suspect 'remorseful,' attorney says

Cruz is being held without bond after he attended via video a brief hearing Thursday in Broward County court.

"He's sad, he's mournful, he's remorseful," said public defender Melisa McNeill, who is Cruz's lead counsel. "He is fully aware of what is going on. He's just a broken human being."

Cruz entered the high school he had once attended on Wednesday at about 2:21 p.m., according to a law enforcement timeline.

In the minutes before the shooting, he exchanged texts with the son of his host family, a student at the high school who was there during the shooting.

They were messaging until 2:18 p.m., said Lewis, the attorney for the host family.

The texts were "very innocuous," Lewis said. "They were just conversations about 'Hey, what are you doing? What are you doing later? What's goin' on?'"

After the shooting, Cruz fled and was detained in a nearby community about 40 minutes later.