A multiday sentencing hearing began Monday in Chicago and focused on whether FBI agents manipulated a mentally fragile teenager to participate in a terrorist plot or whether he had long before shown an eagerness to kill.

Prosecutors called an FBI agent to the witness stand to tell Adel Daoud's sentencing judge that Daoud posted social media comments inquiring about attacking non-Muslims more than a year before undercover agents ever engaged him as part of a sting.

Authorities arrested Daoud in late 2012 after he pushed a button on a remote he believed would detonate a 1,000-pound (454-kilogram) bomb outside a crowded Chicago bar. Prosecutors want a 40-year prison term for Daoud, who entered an Alford plea in November.

Defense attorneys say the now-25-year-old, who grew up in the Chicago suburb of Hillside, is a textbook example of how the agency often snares the psychologically vulnerable in such stings. They want U.S. District Judge Sharon Johnson Coleman to release him as soon as a mental health treatment plan can be developed for him.

The agent who took the stand first, Jeff Parsons, read postings Monday in which Daoud expressed admiration for al-Qaida leader Osama bin Laden, described himself as an aspiring terrorist and even typed keywords like, "I am a terrorist" and "download terrorist magazine," on search engines.

Defense attorney Thomas Durkin suggested during cross-examination later Monday that Daoud's overt and clumsy online chat about being a terrorist should have been a strong sign he was no such thing.

"How many terrorists do you know who have literally proclaimed online that, 'I am a terrorist?'" Durkin asked Parsons. The agent answered he hadn't heard of others.

The agent said he saw nothing in Daoud's postings indicating he suffered from mental illness. He said Daoud showed initiative, suggesting to undercover agents that fitting butcher knives to a truck and driving it into a crowd would be a way to kill many people at once.

Durkin mentioned another idea of Daoud's — to stage attacks by deploying "flying cars." He said that idea should have been one of many red flags.

"Did it ever occur to you ... that the person you were dealing with was unstable?" Durkin asked the agent.

"I didn't see anything indicating he was mentally unstable," Parsons answered.

The agent also read comments Daoud posted admitting he may not have the qualities for a militant, saying, "I got asthma and flat feet. ... And I have never even held a gun before." He added: "I have a terrible case of procrastination and laziness."

In 2016, Coleman temporarily deemed Daoud mentally unfit after ruling that he seemed sincere about assertions that Illuminati and "reptilian overlords" were out to get him.

On Tuesday, prosecutors intend to call an undercover agent who played a central role in the sting against Daoud. Prosecutors say the agent's life would be in danger if his identity is revealed public, so he will either testify in a disguise or from behind a screen.