"Troy and I took an oath to the Constitution and to enforce the laws of the state of Utah," Gill said. "We haven't taken any oath to any political party."
Gill is a Democrat who defeated Shurtleff's preferred candidate, Lohra Miller, in a rematch in 2010. Soon after his election, Gill also ended up in a dispute with the attorney general's office. A losing vendor for an emissions contract in Salt Lake County had alleged collusion and asked the attorney general to investigate. Gill, fearing the AG's office was trying to influence the contract, called in the FBI. A grand jury was convened but never met.
Rawlings is a Republican who was a vocal supporter of Swallow's GOP challenger, Sean Reyes, in 2012 and criticized Swallow on Twitter.
Swallow's attorney, Rod Snow, supported Gill when he ran for district attorney and said he respects Rawlings, but noted there have been tensions between Swallow and the two county prosecutors.
"They're both good men, and they're both professionals," Snow said, "but I think they should be very concerned that any time you get political concerns mixed up in a criminal investigation, that's not a good brew. You really need someone who is totally independent and who hasn't had friction with the subject of the investigation."
Snow said he didn't have the same concerns with the Justice Department, which decided earlier this month against filing charges against Swallow or Shurtleff.
For his part, Shurtleff says he's had good relationships with Gill and Rawlings, but wonders why they are still investigating.
"You have to ask the question why those two aren't conflicted out," Shurtleff said, speaking recently on the conservative Red Meat Radio program.
Shurtleff said Gill was upset when he twice endorsed Miller, giving more than $50,000 to her campaign and doing ads for her. Likewise, Shurtleff said, he and Swallow, his handpicked successor, have a history with Rawlings.
"He didn't just endorse Sean Reyes. He was there at his booth at the convention. He was out tweeting very negative things about John Swallow, about me, frankly, and about the office," Shurtleff said. "So you have to wonder why Sim Gill picked Troy Rawlings as an assistant ... in his investigation."
Rawlings' Twitter postings from early 2012 mentioned several Swallow accusers including indicted entrepreneur Jeremy Johnson and jailed businessman Marc Sessions Jenson and referenced a proposal by Swallow to move the state Division of Consumer Protection into the attorney general's office.
"Tired of frauds being friends of Utah AG Chief Deputy [Swallow at the time] who wants to bring Fraudsumer Protection in house. Go Sean," he tweeted.
Rawlings has since deleted the tweets, but acknowledged using the accounts.
"When you have that in the background," Shurtleff said, "you have to start asking [questions]."
University of Utah law professor Paul Cassell said belonging to a political party, in Gill's case, isn't problematic top prosecutors are political offices in Utah.
But Rawlings discussing matters that he later would investigate, Cassell said, does raise questions about his impartiality.
"It seems to me those tweets, which seem to be taking sides in the Swallow-Jeremy Johnson debate, do raise a substantive question about the appearance of partiality," Cassell said, "because a prosecutor having taken sides on a particular issue shouldn't then be investigating which side of a particular issue is true."
Gill and Rawlings insist they have taken pains to be aboveboard and nonpartisan in their probe. Indeed, recognizing the likelihood their objectivity would be questioned, they sent a letter to fellow county attorneys July 17, seeking to assemble a group of Swallow supporters to review the evidence and decide if criminal charges are warranted.
"We are keenly aware that any decisions we make about this matter will be attacked and questioned," Rawlings wrote. "Obviously we want the process and decisions [to] be fair, objective and impartial. The general public must see that both process and outcome, no matter what direction the case goes, were not motivated by a skewed agenda."
Several county attorneys have agreed to participate, but Gill and Rawlings declined to name them.
Rawlings said the prosecution team which includes the FBI and investigators from the Utah Department of Public Safety would base their decisions on the evidence.
"We will perform our sworn duty despite public-relations campaigns," Rawlings said in a statement. "The primary investigative agencies, the FBI and DPS, are not rowing oars as a result of tweets."
Gill said despite "cynicism," he and Rawlings would not "abdicate our responsibility to hold officials accountable."
"We're public prosecutors first, and we recognize our responsibility and the public trust that adheres to this responsibility," Gill said. "That is why we have taken the steps we have taken to ensure the integrity of that process, and we will continue to do so."
The letter also sheds additional light on the investigation. As of July, Rawlings wrote that there were 10 sections of criminal code that may be applicable to the matters they were examining.
And the prosecutors were looking to the Utah House probe of Swallow to turn up additional information, although there were concerns about the statute of limitations lapsing on some matters.
The special House investigative committee issued two sweeping subpoenas to Swallow and the attorney general's office Thursday the first the panel has sent. The move came even as some House members, in light of the DOJ decision not to prosecute, are urging that the committee shut down its probe.