Antonio Martinez — aka Muhammad Hussein — was pretty sure he was being set up. A car bomb had been handed to him, and two volunteers he barely knew were suddenly on board with a jihadist plot to murder military personnel in Catonsville.

But once he got close to the rigged SUV that December day and got a whiff of the "fumes" emanating from it, he started to think "maybe it was real" — and when he got behind the wheel, "he felt certain," according to paperwork filed in federal court Tuesday.

The 30-page document, submitted by federal prosecutors, reveals new information about the "full confession" Martinez allegedly made to the FBI and how a confidential informant helped build the terrorism case against him.

Martinez was a recent convert to Islam who thought of himself as a radical "holy warrior" when he parked the vehicle at an Armed Forces recruiting center, where he believed the bomb would have more "umph," the filing states. He left the scene, and waited for the man he knew as an "Afghani brother" — actually an undercover FBI agent — to confirm "that at least six soldiers were in the building" before attempting to "detonate the device" using a remote control.

Federal authorities arrested Martinez Dec. 8, after he allegedly tried to set off the inert vehicle bomb that agents had supplied.

The court filing responds to earlier claims from Martinez's public defenders. They say investigators induced the 22-year-old's participation in the plot and violated his constitutional rights by failing to record his confession and several early conversations with an unnamed informer who was posing as a conspirator.

"This [recording] failure by law enforcement authorities was done in a bad faith effort to insulate those early, critically important meetings from any scrutiny and to deprive the defense of essential and potentially exculpatory evidence,' Martinez's lawyers wrote in a court document filed this summer.

They've asked for a dismissal of the indictment, which charges Martinez with the attempted murder of a federal official and the attempted use of a weapon of mass destruction, and the suppression of most evidence against him — including his own statements. A judge has yet to rule on the requests or grant a hearing to discuss the issues.

Prosecutors countered Tuesday that the claims are unsupported, that Martinez masterminded the bombing effort and that the unrecorded conversations were, in fact, documented — in written form. They outlined the contents in detail, under the heading "summary of evidence."

The confidential informant on his own came across Martinez's public Facebook page, which displayed "extremist views" about swords ending the "reign of oppression" and hatred toward "any 1 who opposes Allah," prosecutors said.

The man recognized Martinez as someone he had seen at a mosque and informed the FBI about the social media postings on Oct. 8. The agency then gave him "permission to speak" to Martinez and told him to report back.

The informant and Martinez communicated several times through Facebook and in face-to-face meetings at a mosque, a gas station and other locations, prosecutors said. The source emailed the FBI details of the conversations after they occurred.

In one digital discussion, the defendant "said it was his dream to be among the ranks of the mujahideen [holy warriors] and he hoped Allah would open a door for him because all he thinks about is jihad [holy war]," according to prosecutors. A few days later, he talked of "attacking Army recruiting centers" and obtaining guns, and targeting military installations, the court filing said.

The FBI opened a formal investigation into Martinez after debriefing the informant on Oct. 27, but permission to record conversations wasn't granted until Oct. 29, authorities said — a day after Martinez reportedly told the informant he wanted to attack the Armed Forces Career Center on Route 40 in Catonsville.

An FBI agent posing as an "Afghani brother" soon introduced himself and floated the idea of a car bomb, eventually supplying the phony explosive that led to Martinez's arrest and supposed confession.

Defense lawyers could not be reached Tuesday, but they said in legal filings that there's no way to tell if the confession and talks of targeting the center are true without a recording, and that the lack of one violates Martinez's "Fifth Amendment right to due process, and his Sixth Amendment right to put on a complete defense."

Prosecutors declined to comment through a spokeswoman, but noted in court documents that most conversations with Martinez were recorded and that he "repeatedly made statements throughout the investigation that reflected that the attack on the recruiting center was his [idea] and his alone, which he subsequently confirmed … post-arrest."

Martinez told FBI agents that he was suspicious that the attack was a setup but grew more confident after getting into the SUV and parking it where "it would level the front [of the building] where the soldiers were and insure they died," prosecutors said. And he knew he was either going to be successful, or get "locked up," court documents claim.

Agents claim he told them he "would accept the consequences of his actions."

tricia.bishop@baltsun.com