ALLEN PARK, Mich. -- Matt Patricia's 1996 arrest and indictment on a charge of aggravated sexual assault in Texas came as a surprise to his NFL employers.

The Detroit Lions said they didn't know. The New England Patriots, in a statement, said they were unaware, as well.

But how did that happen?

In one respect, it's difficult to understand how the Lions missed it, since Patricia's indictment came up in a basic Lexis search -- initially proved by Deadspin and later done by ESPN.

There is an error in that search -- one that likely would have prompted more questions from the Lions, had they found it -- that says the alleged crime committed involved a child. Court records have shown that is not true.

It's worth noting that the media, including ESPN, also missed this element of Patricia's past during his 14 seasons in New England and when he was interviewing for head-coaching jobs in recent years, up until The Detroit News reported on the decades-old case Wednesday evening.

How could this have happened? What might the Lions have done differently to discover the case instead of saying they first learned about it from a News reporter this week?

The Lions' front office didn't offer an explanation in the statement it released to the media Wednesday night, hours after the News broke the story. The franchise told the News, though, that its background check searched only for criminal convictions.

"Coach Patricia was the subject of a standard pre-employment background check which did not disclose the issue," the statement said.

That they searched only for convictions would make sense if the franchise outsourced the pre-employment check to a third party -- something common for many big companies. Many background search firms will give felony/misdemeanor arrest information going back only seven years because the Fair Credit Reporting Act does not allow background check reports done by consumer reporting agencies to dig deeper than that.

"Typically, per federal law, it can show conviction records indefinitely, arrest records for only seven years," said Ryan Howard, the vice president of business development for VeriFirst Background Screening. "So non-convictions, it had to have happened in the past seven years. If it's outside of the last seven years, you can't show a non-conviction.

"If it's a conviction, you can show it indefinitely."

Howard said because it was 22 years ago and not a conviction, the Patricia case would not show up in a background check being used for employment purposes. Screening companies filter that potential information out of searches given to their clients because of the law not allowing that to be considered for employment purposes.

The Lions, though, could have found out in other ways. They could have chosen to do a background search on their own -- like reporters have done in the days after the initial Detroit News report -- and found the arrest, although they are legally not allowed to consider that for employment reasons. Howard said, though, that most companies today use third-party screening companies.

Had the Lions been following only Michigan state law, they could have asked Patricia about potential felony arrests. Because Massachusetts state law says employers cannot ask about arrests that didn’t lead to convictions, the Lions were prohibited from potentially asking that question. Patricia resided in Massachusetts at the time and Lions team president Rod Wood told ESPN on Saturday they followed federal law along with Massachusetts and Michigan state laws.

Even if the Lions had just been following Michigan state law, they might not have asked the question anyway.

Nicholas Roumel, an employment attorney based in Ann Arbor, Michigan, said he wouldn't advise companies to ask about felony arrests that didn't result in conviction but added that that is his interpretation of the law -- not the letter of it.

"The general rule in Michigan is employers only ask about convictions," Roumel said. "Since Matt Patricia was not convicted of a crime, most applications that I have seen would not require him to disclose that.

"However, the Michigan Department of Civil Rights interprets the law to permit employers to ask about any felony arrest, even if it didn't result in a conviction."

When Patricia was asked Thursday whether the Lions had asked him whether he had been arrested, he said, "There was never any situation in the Lions interview where I did not disclose the truth."

When asked again whether they specifically asked about any arrests, Patricia didn't give a definitive answer.

"As far as the interview process is concerned, there was nothing that -- and Rod [Wood] had spoke to it earlier, about the process -- there was nothing that I did not answer.”

Wood and general manager Bob Quinn did not speak to the media Thursday, although both attended Patricia's news conference along with team owner Martha Ford. Wood and Quinn were in charge of making the coaching hire after the firing of Jim Caldwell on Jan. 1.

On Saturday, Wood spoke with ESPN about the screening process and said the Lions wanted to follow the law when it came to the hiring process.

"There might be ways for companies, teams in our case, to find information out about a prospective employee through other means than the legal means," Wood said. "I guess if others wanted to do that, that’s their prerogative. I’m only in charge of what the Lions do, and I want to do it the right way."

Editor’s note: This story was updated after more information came to light about the Lions’ hiring process.