In the wake of his arrest, those who knew him and his family are struggling to piece together what happened - how this boy they grew up with and went to school with became the alleged source of such terror.
Rahami, 28, was born on January 23, 1988, in Afghanistan, but he became a naturalised US citizen after his family moved there.
Public records show that the Rahamis bounced around New Jersey during their early years, living in Perth Amboy, Edison, Union Township and Elizabeth, which is six miles south of Newark.
Their most recent address was at the Elizabeth apartment above a restaurant called First American Fried Chicken. Court records show that the family has owned and operated the eatery since 2002.
A childhood friend said he used to play basketball with Rahami at a court a few blocks from the family's restaurant.
"I was shocked to see his picture. I said, 'No, not Mohammed's son.' They were really nice," said Flee Jones, 27. He and Ahmad used to do rap battles at the restaurant and hang out there late into the evening. He said the friends nicknamed Ahmad "Med." And Jones recalled how the family would sometimes give him free food.
The family home and business sits on Elmora Avenue - a street of small businesses, including a hair salon, a dry cleaner and an international supermarket.
"He was always respectful to me," said Jaime Reyes, owner of Sonia's Beauty, next door to the chicken place.
Others, however, recounted a more volatile relationship with the Rahamis.
"They were angry," said Marcella Perrotti, who owns a hair salon across the street. In a small town with a tightknit community, the Rahami family stayed well outside of it all. "They were outcasts," Perrotti said.
There were also signs of violence within the family, said Rep. Peter T. King (R-N.Y.), who is on the House Homeland Security Committee.
King, who has been briefed by the FBI, said Rahami once tried to stab his sister in a domestic violence incident. "My understanding is she accused him of domestic violence," King said, but that when questioned by authorities, "the sister recanted."
King said authorities are also investigating several trips abroad that Rahami took in recent years. "I'm hearing that his trips to Afghanistan changed him. He also went to Pakistan at some point. There were a number of trips," King said.
A federal law enforcement official confirmed that Rahami had taken several trips to Pakistan and Afghanistan over the past five years. The official also said Rahami had a firearms license.
Law enforcement officials said they were investigating whether Rahami could have been influenced by international terrorist groups or the ongoing conflict in his homeland.
A high school classmate said Rahami had become more religious of late.
The classmate, Amarjit Singh, 27, said Rahami clashed with his father after the son started dating a Dominican woman; the couple had a daughter, who is now 6 or 7.
"When he was younger, he had more Western values," Singh said. "After he had his daughter, he became more religious. In the last few years, he was more into the Koran."
Andre Almeida, 24, who lives down the street and often ate at the restaurant, said the family had seemed Westernised. But three or four years ago, he said, he noticed that they started wearing more traditional clothing.
In a 2005 bankruptcy filing, Rahami's father, Mohammed, described himself as the parent of eight children who was separated from his wife. He listed himself as a cook at the restaurant, with an income of US$1447 a month. He said he had accumulated more than US$45,000 in debt and had just US$100 left in his bank account.
Court records show the Rahami family struggled to keep its business afloat and clashed repeatedly with town authorities over the eatery's late-night hours.
In 2011, the Rahamis sued the city of Elizabeth and several police officers, alleging that police were harassing them and inappropriately citing them for keeping their restaurant open past 10pm.
According to the lawsuit - which continued in court for years and alleges civil rights violations - a year after the family opened the restaurant, the city passed an ordinance barring restaurants from operating past 10pm.
The family claimed that a neighbourhood businessman told them: "Muslims make too much trouble in this country," "Muslims should not have businesses here" and "Muslims don't belong here."
Following the businessman's complaints to police, officers starting singling out the family "solely on animus against [their] religion, creed, race and national origin," according to the lawsuit. The family said police and the businessman proceeded to harass, humiliate and intimidate them over the 10 p.m. closing time.
In one instance, they alleged, two Rahami family members were arrested for attempting to record a conversation with police officers.
Talking to reporters Monday, Elizabeth Mayor J Christian Bollwage confirmed the acrimony and said city officials kept getting complaints about rowdy customers and incidents stemming from the late-night hours.
According to classmates, Rahami attended Columbia High School in Maplewood before moving to Edison High School.
In a Facebook posting, Hoda Mitwally, who attended Edison with Rahami and graduated with him in 2007, said she was "in a state of shock" when she saw the news, but she urged fellow classmates not to rush to judgment and to get a lawyer if questioned by the FBI. Mitwally did not return calls or other attempts to reach her.
"There is a lot we don't know yet," she wrote. "Right now, all we do know is that he is a suspect wanted for questioning. So please do not jump to conclusions just yet about whether he did it, because he is innocent until proven guilty."
Just before Rahami's arrest Monday, New Jersey State Police released several images of him, including surveillance footage from one of the bomb locations.
Outside the family's business Monday afternoon, Rahami's father told MSNBC that he had "no idea" his son had been making bombs and planning an attack.
