She was in court while the recordings were being shown to the jury in the trial of Baltimore Police Officer William Porter.
He's the first of six city police officers to go on trial in the closely watched case involving Gray, a 25-year-old black detainee who died after being shackled and placed without a seat belt in a police van. The case set off riots in this port city this past spring.
At the conclusion of this important evidence for prosecutors, Darden began to sob -- the only sound in what was a very silent court room.
Jurors who had been taking extensive notes on the video recordings turned their attention to this mother still overcome with grief.
Judge Barry Williams immediately called for a break as Darden was led out of the courtroom. She later returned for the remainder of the day's testimony.
Testimony on Porter's training
Thursday's testimony started off with John Bilheimer, a 17-year veteran of the Baltimore Police Department who said he had taught defendant Porter his emergency vehicle operation's course at the police academy in 2012.
Prosecutors quickly focused in on a section of the course dealing with transporting people in police custody, showing through testimony that Porter learned at that time about "secure seat restraints," or seat belts, and that they were for the safety of the person being transported. The course also taught, however, the decision to use them was a case-by-case decision so as to not jeopardize officer safety.
Porter's workbook at the time was entered into evidence and answers in his own handwriting were read to the jury:
"We do not transport injured people. We render aid per our training, and contact the medic. We cannot render aid while driving. There are civil liabilities. We risk bodily fluid exposure."
The prosecution is trying to show that Porter had knowledge about seat belt safety during transport of suspects back to 2012, when he was training to be an officer.
Porter has pleaded not guilty to charges of involuntary manslaughter, negligent assault, misconduct in office and reckless endangerment in the case.
Defense focuses on van driver
For the first time in this trial, the defense seemed to place the responsibility for Gray's safety on Porter's colleague and fellow defendant, police van driver Caesar Goodson, whose trial is set for January.
Defense attorney Gary Proctor got Bilheimer to testify that the "wagon operator takes physical custody" and is responsible for those he is transporting.
Capt. Martin Barnes, a veteran of 18 years with the Baltimore Police Department and former supervisor of professional standards and accountability, testified that new department policies were published on April 3, including an order now requiring seat belts on those being transported in the police vans.
More detailed instructions on this new requirement stated the seat belt was to be put on the waist or upper body so the suspect "can't get out of the seat belt and injure themselves."
The defense countered by saying that Porter didn't receive notice of the new policy until April 9, three days before Gray was transported, and there is no way of knowing whether Porter actually read the 80-page attachment that explained the new rule.
It was one of 41 emails Porter received that day.
Witness: Gray was like a brother
Gray's good friend Brandon Ross, who testified he grew up with Gray and had been a friend for more than 10 years, took the stand saying Gray was like a brother to him.
Ross was with Gray the morning he was arrested and testified they were on their way to find an associate of Ross' when Gray turned the corner and just began to run.
The witness explained the layout of the streets of West Baltimore before the jury saw several short videos, all from April 12.
Maryland Transportation Authority video along with Baltimore City Closed Circuit TV showed Gray, Ross and another friend walking the streets of the west side early that Sunday morning.
Gray appears well with no disabilities or health issues in the video.
Two cell phone videos, the first recorded by bystander Kevin Moore, were introduced into evidence despite objections by the defense. Moore's video showed Gray being dragged to the police van after he was arrested. The video was recorded at 8:44 a.m.
Ross, who recorded his own iPhone version of Gray being removed and put back into the van a few blocks away, started his recording at 8:49 a.m.
A lot of the video was shaky on this phone recording, but notable were Ross' audio of "that's not cool" several times as Gray was being prepared for transport.
Prosecutors also had Ross testify that his video included a shot of the defendant pulling up in his squad car as Gray was about to be put into the transport van for the second time. On the recording, you hear Ross asking Porter to help him get a supervisor.
Ross testified that Porter did in fact point to a supervisor and when Ross said, "I'm getting this all on video tape, he testified that Porter replied "take it to the media."
Ross admitted on the stand he knew Officer Porter from previous interactions and Porter knew him. It is the defense's contention that Porter knew Gray from previous interactions and was aware of his history of not complying with police orders.
Jury views police wagon
During the lunch hour on Thursday, the jury had a view of the police wagon in which Gray was transported.
The viewing was closed to the public and media. CNN has objected to that on the grounds that a jury view is part of a public trial and the media has a right of access.
So far, nine witnesses have testified for the prosecution. Court resumes at 9:30 a.m. ET Friday in Baltimore.