Accused mass murderer Nikolas Cruz and arrested brother 'starting' fan club from jail to attract girls, prosecutor says Zachary Cruz is being held on $500,000 bail.

During a bail hearing on Tuesday for mass shooting suspect Nikolas Cruz's brother, Zachary Cruz -- who allegedly disregarded warnings and returned Monday to skateboard on the Marjory Stoneman Douglas High School's campus -- a state prosecutor accused the brothers of "starting" a penpal or fan club to attract girls.

Sarahnell Murphy, assistant state attorney, announced the shocking revelation Tuesday after ticking the 18-year-old's prior crimes, which included "three crimes of grand theft, criminal mischief and petty theft" during 2016.

Zachary was arrested at 4:30 p.m. Monday afternoon for allegedly skateboarding through school grounds, according to the Broward Sheriff's Office arrest report.

"Most concerning is the contact he's had in jail with his brother since his incarceration," Murphy said. "He has been heard and observed discussing how popular his brother is now.

"That his face is everywhere and his name is national."

She went on to add that the brothers allegedly have been revelling in the infamy.

"There is a discussion of starting some kind of penpal or fan club and see how many girls he is capable of attracting -- referring to his brother Nikolas," Murphy said.

Nikolas stands accused of slaughtering 17 students and teachers on Valentine's Day at the Marjory Stoneman Douglas High School in Parkland, Florida.

Nikolas was arraigned March 14 on a 34-count indictment related to the South Florida high school massacre, for which the 19-year-old is now facing the death penalty.

A plea of not guilty was entered on his behalf, though his defense attorney has been willing to have him enter a guilty plea if he could be spared and serve life in prison.

When questioned on Monday after skateboarding on the school campus, Zachary allegedly told the arresting deputy he wanted to “reflect on the school shooting and soak it in." Murphy also noted that Zachary admitted it wasn't his first time on the school grounds since being warned.

"He admitted this was not the first time he had been present on the school campus but it had been the third," Murphy added before urging the judge to notice that Zachary possessed "all the same [red] flags present as his brother [Nikolas]."

She claimed that Zachary's return an alleged third time to the same school that had been a crime scene a month ago -- despite not living in the county -- wounded an already scarred community.

"The nature of probability of intimidation and danger to these victims was demonstrated today in Broward County when the parents became aware of [Zachary's] presence on campus and many kept their children home from school today," Murphy said. "They have again been terrorized."

Joseph Kimok, who is Zachary's attorney, tried to ask that the judge release him on a "standard" $25 bond fee, which he said his client already paid.

He also claimed the state prosecutor was blaming Zachary for his older brother's alleged mass murders.

"All the requests the state just made are not for skateboarding through the school grounds," Kimok said. "Mr. Cruz, it's well documented, he lost his mother recently and he lost his brother in an unimaginable way. For the state to request $750,000 bond with all of the conditions they are requesting is simply a punishment for who he is related to."

The judge was unmoved.

Though she didn't impose $750,000 as the state prosecutor requested, she considered "the totality of circumstances" and set bail of $500,000 and a raft of restrictions.

She barred Zachary from any further contact with Nikolas, stating, "that he not have contact with his brother direct or indirect."

And should Zachary post bail, he would be mandated to wear a GPS ankle monitoring device.

The judge also forbade him from contacting anybody affiliated with Majory Stoneman Douglas High School, to keep a mile away from the school campus and 500-feet away from any other school campus or child care facility "at all times."

Cruz's home, the judge also stated, was ordered to be searched for any "guns, weapons or any ammunition." Zachary was also ordered to stay away from Broward County entirely unless it is to meet with his attorney or attend court.

ABC News' Rachel Katz contributed to this report.