In a city with a notoriously high murder rate propelled by turf skirmishes and youthful recklessness, “Urkel” was a different breed of killer, and perhaps the most efficient, cocksure triggerman in New Orleans, according to federal allegations against him.

Yet it’s unclear when or even whether Walter Porter, portrayed by authorities as the go-to hit man for accused Central City crime kingpin Telly Hankton, will face prosecution.

That’s not because Porter is ready to cooperate with the government in any of the three separate federal cases hanging over his head. In fact, he has refused even to enter not-guilty pleas in two of them.

Porter, 39, was last seen in a New Orleans courtroom a year ago last week, balking over the appointment of his attorneys and complaining about underhanded actions by Mayor Mitch Landrieu’s administration — as well as the mayor’s brother, Assistant U.S. Attorney Maurice Landrieu, who heads up gang prosecutions for the U.S. Attorney’s Office.

For most of the time since then, Porter has been in a federal medical facility in the Nashoba Valley of Massachusetts, on a former Army base an hour’s drive from Boston. There, he is free to meander the walking trail behind the minimum-security prison’s fence, a prison official said.

She declined to discuss Porter in particular, citing a judge’s competency order holding him there until he’s deemed capable of assisting in his defense.

The bespectacled Porter — his eyewear helped earn him the “Urkel” moniker, a nod to the geeky character in the 1990s sitcom “Family Matters” — can also write letters, such as the various lengthy screeds he has penned to federal judges, President Obama and others, demanding a federal investigation into what he describes as an unconstitutional pile-on job by prosecutors.

Neither his lawyers nor prosecutors will discuss Porter’s mental condition, citing a gag order in the federal gang racketeering case involving Hankton, Porter and 11 other defendants. All reports related to Porter’s mental health status remain under seal.

In the meantime, his remaining co-defendants in the two other federal cases against him have either pleaded guilty or pressed to move to trial on their own, fearing further delays caused by Porter’s court-ordered absence — as well as any association with a man whom federal prosecutors have linked to at least nine murders and six bank robberies.

The attorney for London “Luchie” Carter, Porter’s lone remaining co-defendant in a case accusing them of two armed bank robberies, asked a judge again last week to let Carter proceed to trial alone on May 11, citing Porter’s “continued and extended unavailability” after seven delays.

The federal judge handling the case of a 2010 hit job that the government says Porter carried out already has agreed to let the man who allegedly ordered the hit, Nemessis Bates, stand trial alone on June 1; the judge cited the uncertainty about when Porter will be ready to appear as the reason.

And in Porter’s absence, Hankton; Hankton’s mother, Shirley; and 10 others are gearing up for a blockbuster trial scheduled for August on allegations of running a bloody drug ring for decades.

The indictment in that case names Porter in three murders, including the October 2012 killing of Curtis Matthews, the brother of a key eyewitness to an earlier killing by Hankton. That brother, John Matthews, survived 17 gunshots — allegedly from Porter — to testify against Hankton in a 2008 murder on South Claiborne Avenue. In the Hankton indictment, Porter is described simply as “gunman for the enterprise.”

According to the allegations and public records, Porter was an efficient and prolific assassin who used the same firearms repeatedly, hanging them from fishing line behind the walls of his Uptown home.

He also was careful. Porter once called off a targeted killing when a cohort — rapper Christopher “B.G.” Dorsey — got too high, according to a transcript of a jailhouse phone call.

Porter, who also went by the nickname “Moonie,” didn’t kill only on Hankton’s behalf, and hit jobs weren’t his only lucrative venture, authorities claim.

Of the nine killings over three years that prosecutors have tied to Porter and his guns, four came in 2011, while Porter was also busy robbing banks, according to the feds.

He is accused of a pair of brazen armed robberies that summer that netted $134,000 from Capital One branches in New Orleans and Metairie.

In the Metairie robbery, on Aug. 26, 2011, Porter and three other men first met at his house on South Liberty Street, where Porter handed out guns to the two other men, Carter and Brian “Beano” Hayes, authorities allege. Porter then held an assault-style rifle as the group pointed their weapons at tellers and customers, according to plea statements from Hayes and a driver in a second, getaway car, Terrance Lodrig.

But as they drove off with a pile of money, the dye packs in it exploded and Porter veered into a curb, causing a flat tire. Lodrig picked them up and the four men took the ink-stained money to launder it, literally, in washing machines. When that didn’t quite work, a group of men took the pink cash to Harrah’s to funnel it through change machines and slots, court records show.

That was among a half-dozen bank jobs that prosecutors now link to Porter.

Carter’s attorney, Catherine Chavarri, who filed a new motion to split him off from Porter in the bank robbery case, said last week she is preparing for the May 11 trial date, with or without Porter. Court records show Carter recently pulled out of a pending plea deal in the case.

“I don’t know what to expect. I don’t know whether the government or attorneys for Mr. Porter are going to ask for a continuance,” Chavarri said.

In a third federal case, Porter is accused of carrying out a $20,000 hit job in 2010 for which he wasted little time.

One of his co-defendants claimed Porter fired 20 bullets into his target, Christopher “Tiger” Smith, the day after receiving the job. When Porter came to collect his fee from Nemessis Bates, at Nemo’s Carwash on Tulane Avenue, Bates didn’t seem to have expected such a businesslike approach to the work, according to a third co-defendant, Aaron Smith, who pleaded guilty in the case.

Porter took two of Bates’ cars as collateral until he got paid his half-share, Smith told authorities.

U.S. District Judge Sarah Vance agreed in September to allow the case against Bates to go forward on its own, citing the delay but also the potential “spillover effect” from the other murder allegations against Porter and, at the time, Porter’s eligibility for the death sentence.

In January, U.S. Attorney General Eric Holder’s office took the death penalty off the table for Porter, Hankton and three other defendants in the federal racketeering case.

Porter’s attorneys, Marilyn Fournet and Robert Toale, have declined to discuss Porter’s case, citing the gag order.

If his appearances in court last year and in late 2013 are any indication, Porter doesn’t want them speaking for him anyway.

Last year he refused to acknowledge even that his lawyers represented him. In one hearing, bailiffs had to wrestle him out of the courtroom.

In court hearings, Porter repeatedly ranted to judges, claiming he’s the victim of an unconstitutional prosecution.

“My life is in danger and Maurice Landrieu telling me to my face that he will see to it that I will get the death penalty if I don’t work for them, you know,” Porter exclaimed to U.S. Magistrate Judge Karen Wells Roby a year ago. “And he told me the only one who could help me is Obama, to my face, ma’am.”

He continued, claiming to be quoting Landrieu: “ ‘And we will see to it with the power of the Landrieu administration that I, Walter Porter, will get the death sentence and I will die.’ He said that hisself. And I been traumatized ever since then and I request to get taken from this bench, and it’s unconstitutional what is going on to me.”

That was in April 2014. Porter hasn’t appeared in a federal courtroom since.

Landrieu, the prosecutor, declined to comment, citing the gag order in the Hankton racketeering case.

Earlier, Porter complained that his attorneys refused to file motions at his request and that he was left in the dark when new indictments sprang up. He also griped about his past isolation under federal custody in the St. Bernard Parish jail.

Porter has asked to meet with U.S. Attorney Kenneth Polite and to appear before a grand jury to air his grievances.

Despite his frustrations, Porter rebuffed a prosecutor who commented at one court hearing that he has the right to represent himself.

“No, ma’am,” he told the judge. “That’s foolish of me to do so. And for him to even bring it up.”

It’s unclear when the court will revisit Porter’s ability to assist in his own defense or when he might return to the courtroom.

“Your honor, I’m not 100 percent sure what to do with Mr. Porter,” Assistant U.S. Attorney Elizabeth Privitera commented at another hearing last year in which Porter repeatedly interrupted U.S. District Judge Stanwood Duval. “It’s my impression Mr. Porter is never going to be content.”

Follow John Simerman on Twitter, @johnsimerman.