Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

ASHKELON, Israel — It looked like any normal bedroom inhabited by a geeky Israeli teenager: a Hebrew-English dictionary on the bookshelf, a game of Monopoly, and a small microscope on the desk.

But it was here, in an upscale apartment in the Israeli coastal city of Ashkelon, that officials say a 18-year-old Israeli-American Jewish kid wreaked havoc across America.

The teen is accused of calling in more than 100 bomb threats to Jewish community centers across 30 states earlier this year. The threats caused evacuations at Anti-Defamation League offices from New York to Wisconsin and were denounced by President Donald Trump as "horrible and painful."

Authorities said the teenager, who U.S. officials identified as Michael Ron David Kadar, used sophisticated techniques to hide his identity and was only caught during an international operation involving the FBI. He has been in police custody since he was arrested on March 23, and was formally charged by the Justice Department on Friday. The Israeli police are also expected to charge him on Monday with up to 18 criminal counts, according to his lawyer.

Earlier this month, Kadar's mother gave NBC News special access to her home. She defended her son by claiming his alleged behavior was caused by serious health problems.

"After the police were here, and when I understood what he did, I was shocked and horrified," she said.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

She said she had no idea what her son was allegedly up to, and that the first she heard about the bomb threats was on the news. "I thought it was done by someone who is anti-Semitic," she said.

An Israeli court had banned media organizations from publishing Kadar's name, although American journalists were not subject to the same restrictions. His mother spoke with NBC News on condition of anonymity.

She claimed her son has a brain tumor and suffers from autism, conditions that she said explain his behavior. She declined to allow NBC News to speak with Kadar's doctors to verify her claims.

She called for "police to release my son. And for him to receive the proper medical treatment and remove this terrible tumor so he can have a normal life."

Her plea for medical intervention will not be an easy task since the family's own lawyer, Shira Nir, told NBC News that even "the best surgeons in the world refused to operate on him due to immediate danger for his life."

Nir said that the teenager "suffers from severe and complicated medical problems, which include a tumor on the brain."

Missing from the bedroom during NBC News' visit were the laptop and small antenna that officials say the teenager used to instill fear and chaos some 6,000 miles away. Police allege the teen used the antenna to connect to a variety of different WiFi networks to mask his identity and make the phone calls to the U.S. via his laptop. The police took away the items as evidence after arresting the teenager.

Kadar was born in 1998 to an American mother and Israeli father and the family moved to Israel when the son was 5 years old.

His mother told NBC News that she always knew her son was different.

"As he got to 2 years old, I started noticing he was doing things that showed high intelligence and other things that were not fitting," she said.

She said his kindergarten teachers also noticed he was smart, but reported that he couldn't sit still and was unlike any child they had encountered before.

His mother said "there were strong signs of autism" and decided to homeschool Kadar.

For the next 14 years, he stayed home. He never went to elementary school or high school, didn’t have any friends and hardly left his apartment. At age 18, he was exempted from compulsory army duty.

He loved animals and geography and obsessively painted maps, his mother said. According to her, he was an avid collector of marbles, coins, bus tickets, and foreign currency notes all neatly placed in stacks of albums.

"I understand now the terrible consequences this tumor has on his behavior," she said. "I want to apologize for his actions in his name because he doesn't know what he has done."