A suicide note found on a discarded laptop may reveal a key difference between the Brussels and Paris attacks

A suicide note on a laptop left in a garbage can, believed to have been written by one of the suspected Brussels bombers, has offered new clues into the motivations behind the attack that killed 31 people and injured hundreds more Tuesday morning.

Belgian national Ibrahim El Bakraoui, a suspect in the bombings who died in Tuesday's terrorist attacks, apparently wrote in French that he was in "a bad situation" and that if he did not act immediately, he would end up in a prison cell "like him."

The note may allude to the arrest of Saleh Abdeslam, a suspect in November's Paris attacks who was detained in Brussels last week after four months of evading capture. Abdeslam is believed to have played a role in organizing and planning the Brussels attacks before his arrest, authorities have said.

But experts say it may also indicate that the Islamic State, also known as ISIS and ISIL, may not have had as big of a hand in directing the Brussels attack as it did with the attacks across Paris that killed 130 people last November.

Significantly, El Bakraoui's note - in which he expresses a fear of going to prison and a need to rush the attacks before getting caught - suggests that ISIS "higher-ups" might not have had as much control over the Brussels bombings as they did over the Paris attacks.

"Basically the implication is that ISIS might not be directing things as closely as Paris," terrorism expert Mia Bloom, a professor of communication at Georgia State University and author of two books on terrorist-recruitment methods, told Business Insider on Wednesday.

"My read is that they were clearly planning something - but might have expedited the attack because Abdeslam is being interrogated by the police. In theory a better date for an attack would have been Easter, for example," Bloom added.

Will McCants, author of "The ISIS Apocalypse," agreed that the note seemed to indicate that the attackers had moved up the date of the attack in light of Abdeslam's arrest on Friday.

"The note would confirm the speculation that the attackers moved up the timetable because Abdeslam was arrested," McCants told Business Insider on Wednesday.

But it also raises questions about how much El Bakraoui - and, presumably, his brother and fellow suspect Khalid El Bakraoui - straddled the line between lone-wolf and ISIS operative.

"Maybe it means that this set of suicide bombers started out as just sympathizers to ISIS, sort of tourist terrorists," Chris Harmer, a terrorism expert and senior naval analyst at the Institute for the Study of War, told Business Insider on Wednesday.

"Maybe they never had any intention of winding up as active members of ISIS, but because they had helped Abdeslam and his crew at some point, they feared winding up in jail for the rest of their lives, so decided to go out in a blaze of glory," he added.

Harmer cautioned, however, that it's still too early in the investigation to determine the note's authenticity.

"It's hard to read anything into a note written under duress. Maybe it was a misdirection, intended to confuse the investigation," he said.

Bloom, however, offered that the delayed release of ISIS' online newspaper seems to indicate that the jihadists may have had to scramble to put together a claim of responsibility after the bombers decided - possibly unilaterally - to expedite the attacks.

"The ISIS newspaper, which is released online, was postponed a few hours in order to claim the credit for the attacks," Bloom said. "ISIS says they planted seedlings" for the attack.

McCants noted that the extent of the suicide bombers' connection to ISIS rests on whether or not Najim Laachraoui, ISIS' apparent bomb-maker, was involved in the attack.

"Laachraoui would have been their handler," McCants said.

Ibrahim El Bakraoui and his brother, Khalid, were named as suicide bombers in the attacks by the Belgian police on Wednesday morning.

Ibrahim is thought to have detonated his explosives at the airport, killing at least 10 people, while his brother is thought to be responsible for the suicide attack at the metro station that killed 20 others.

The police have not yet identified their third suspect - the man wearing a light jacket in a photo released by Belgian authorities - but say he is still on the run.

His bag apparently contained the largest of the three explosives that were brought to the airport. That explosive did not go off with the other two and was detonated in a controlled explosion by the police. The man in the far left of the CCTV photo also has yet to be identified.