FORT LAUDERDALE, Fla. (AP) — The Florida deputy on trial for allegedly failing to act during the Parkland school massacre and his colleagues were severely hampered by radios widely known to work poorly in that region, the dispatcher who coordinated the response testified Friday before the defense rested its case.

Samantha Oakley told former Broward County Deputy Scot Peterson's jury that — even before the Feb. 14, 2018 murder of 17 people at Marjory Stoneman Douglas High School — it was known to dispatchers, deputies and administrators that the county's radio system often failed in Parkland.

From the first minutes of the shooting, the system repeatedly failed as more and more deputies tried to radio information as they arrived at the suburban Fort Lauderdale school where Peterson was the on-campus deputy. Instead, the deputies got a tone that was the equivalent of a busy signal.

Peterson’s primary defense to the felony child neglect charges is that the gunshots’ echo made it impossible for him to pinpoint the shooter and that the radio system's failure made it impossible for him to hear what most arriving deputies were seeing and hearing.

Oakley said, “Deputies could not hear what I was saying and also deputies wouldn't be able to hear each other." She had only been on the job for seven months and was on the last shift of her employment probationary period when she found herself handling the initial response to the massacre.

Deputy Arthur Perry, who arrived at Stoneman Douglas during the shooting, testified Friday that when he tried to use his radio he only got a “bonk, bonk, bonk” noise.

Oakley said that another major problem during the shooting was that the 911 cellphone calls students and teachers made from inside the three-story 1200 building reporting shooter Nikolas Cruz's location didn't go to the Broward County dispatch center, but instead went to Parkland's neighboring city of Coral Springs. Its police officers worked on a separate radio system from the county and it was transmitting without issues.

That meant responding Coral Springs officers knew Cruz's location, but Peterson and other Broward deputies were never told about those calls. The Coral Springs radio calls could have been merged into the Broward system during the shooting, but that required a supervisor's order and it never came, Oakley said. She said the merger could have been completed “with three clicks of a mouse.”

Shortly after Oakley and Perry testified, Peterson attorney Mark Eiglarsh rested his case with Peterson choosing not to testify. Circuit Judge Martin Fein will instruct the jury not to hold that against him. Closing arguments are scheduled for Monday.

Fein rejected Eiglarsh's motion to summarily acquit Peterson, even though he appeared skeptical that the prosecution had proven that the deputy was a “caregiver” to the students — one of requirements of felony child neglect. Florida law defines a caregiver as “a parent, adult household member or other person responsible for a child’s welfare.” Caregivers are guilty of felony neglect if they fail to make a “reasonable effort” to protect children or don't provide necessary care.

David S. Weinstein, a Miami defense attorney not involved in the case, said Peterson's testimony would likely have done “more harm than good" given that jurors may also be skeptical that he was a caregiver.

“His expected testimony would be, ‘I did all that I thought I could given my training, experience and the circumstances’ On cross, they (prosecutors) could dig into how unreasonable and negligent his actions were,” Weinstein said.

Eiglarsh focused his two-day defense presentation on the testimony of teachers and students who were near Peterson and also thought the shots were being fired outside or in other buildings.

Prosecutors concluded their two-week presentation Wednesday. They called to the witness stand students, teachers and law enforcement officers who have testified about the horror they experienced and how they knew where Cruz was. Some said they knew for certain that the shots were coming from the 1200 building. Prosecutors also called a training supervisor who testified that Peterson did not follow protocols for confronting an active shooter.

Peterson, 60, is charged with failing to confront Cruz before the gunman reached the classroom building’s third floor, where six of the victims died.

Peterson is not charged in connection with the deaths of 11 people killed on the first floor before he reached the building.

If convicted, Peterson could technically be sentenced to nearly 100 years in prison — although a sentence anywhere near that length is unlikely given his clean record. He could also lose his $104,000 annual pension. He had spent nearly three decades working at schools, including nine years at Stoneman Douglas. He retired shortly after the shooting and was then fired retroactively.

Cruz, a 24-year-old former student, pleaded guilty and received a life sentence last year, avoiding a death sentence when his jury could not unanimously agree he deserved execution.