With the mysteries of when U.S. Cory Booker will plunge into the 2020 presidential race and what former Gov. Chris Christie will say in his air-brushed memoir settled, Trenton tries to answer another open question: Who hired Al Alvarez?

The pursuit of the elusive answer is expected to continue Tuesday in Trenton. It seems no one can explain how Alvarez, an operative on Phil Murphy's 2017 campaign, was able to land a $140,000-a-year job at the Schools Development Authority despite being shadowed by an accusation of sexual assault.

The allegation surfaced during Murphy's transition and took shape when Katie Brennan personally shared details of her accusation with top Murphy administration officials last year.

Testimony before the legislative panel investigating the case paints an unflattering picture of an alarmed Murphy administration meekly urging Alvarez to leave his job. Yet it wasn't until Brennan told her story to the Wall Street Journal last October that an embarrassed Murphy administration finally decided to cut him loose.

Alvarez, through his attorneys, denies the allegations. The Hudson County Prosecutor's Office declined to bring charges against Alvarez in December 2017, and the Middlesex County Prosecutor's Office, which reviewed the case in the wake of the controversy, also chose last month not to charge Alvarez.

The Legislature, meanwhile, vowed to try to get to the bottom of what happened and to recommend ways to reform hiring practices.

But so far, they can't seem to get an answer to the most fundamental question of Alvarez's hiring, prompting Assemblywoman Nancy Munoz, R-Union, to wonder, somewhat facetiously, if Alvarez simply waltzed into Trenton one day and hired himself.

"You would think at this point someone would come forward and say: I did it,'' Munoz said of the hiring.

Lynn Haynes, who is scheduled to testify Tuesday, might offer some clues. Haynes, director of personnel during Murphy's transition, signed a document that authorized Alvarez's hiring. That makes her the person who finally might reveal who gave her the green light to sign off on the hiring.

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Yet after watching top administration officials deny knowledge of and shrug off responsibility, panel members are not optimistic that Haynes will unlock the mystery of the hiring.

"Don't make any book on that,'' said Senate Majority Leader Loretta Weinberg, D-Teaneck, co-chairwoman of the panel.

To some, the repeated non-answers to who hired Alvarez are an example of Murphy officials systematically stonewalling to protect their boss, giving him a position to plausibly deny knowing anything about the entire mess.

Or it could be a symptom of a chaotic, inexperienced administration. In any case, here is a rundown of what top Murphy administrative officials have told lawmakers when asked about the hiring.

Matt Platkin, Murphy's chief counsel. Platkin has been at the nerve center of the controversy and set in motion the move to dismiss Alvarez after Brennan personally shared with him her accusation that Alvarez sexually assaulted her in her Jersey City apartment in April 2017 after a social gathering of campaign workers.

"I don’t, unfortunately, have knowledge of who hired Mr. Alvarez," Platkin testified.

Raj Parikh, senior counsel to the transition team. Parikh related how the Murphy transition team used a color-coded system to classify job seekers who underwent a largely cursory background check. Yet he had little to say about Alvarez's hiring.

"Unfortunately, I do not know the answer to that question, nor would I have ever known the answer to that question. I had no authority in placement recommendations made during the transition,'' Parikh said.

Pete Cammarano, Murphy's former chief of staff. Cammarano was asked by lawmakers who offered Alvarez the job. He replied that it "was a very hectic time ... where we were wrapping up the transition, getting ready to start government. So I don’t know the answer to that."

Jose Lozano, executive director of Murphy's transition team. Lozano denied hiring Alvarez, even though Charles McKenna, who stayed on as director of the Schools Development Authority as a holdover from Christie's administration, testified that he received a text from Lozano informing him that Alvarez would be his new chief of staff.

Alvarez "clearly had conversations with someone else. He did not have them with me, nor did he get my prior approval, because it was not my approval to give,'' Lozano testified.

Brendan Gill, Murphy's former campaign manager. Gill denied any role in Alvarez's hiring in an interview with NorthJersey.com and the USA TODAY NETWORK New Jersey. “I didn’t have any role in transition … I just wasn’t involved in any part of that process, so no,” he said.

Gov. Phil Murphy. Asked during an appearance of "Ask Governor Murphy" Monday night, Murphy was asked if he knew who hired Alvarez. His response: "The answer is I don't know."