Georgia Southern quarterback Shai Werts (4) is pressured by Clemson's Xavier Thomas during the first half of an NCAA college football game Saturday, Sept. 15, 2018, in Clemson, S.C. Credit: Richard Shiro | AP

Shai Werts was baffled. The star quarterback at Georgia Southern University had just been pulled over for speeding in rural Saluda County, South Carolina. Now, a police officer was insistent that a white substance smeared on his Dodge Charger’s hood was cocaine.

“That’s bird s—. I swear to God,” Werts, 21, told the officer, in an exchange caught on a dash cam. “Can I tell you something? That’s bird s—.”

The Saluda County Sheriff’s officer was incredulous. “It looks nothing like bird poop, man,” he said. “We know what bird poop looks like.”

When his field testing kits came back positive for cocaine during the July 31 traffic stop, he arrested Werts. The drug charges sparked national headlines and left the quarterback briefly suspended and in danger of missing GSU’s season opener later this month against national powerhouse LSU.

But Werts was right: That substance wasn’t cocaine. On Thursday night, South Carolina prosecutors told local media that the drug case was being dropped.

“I was informed that the test did come back and that there was no controlled substance found,” Al Eargle, a prosecutor for the region including Saluda County, told the Savannah Morning News.

Werts’s case is the latest high-profile example of the unreliability of field-testing drug kits, which in recent years have come back with false positives on everything from Krispy Kreme doughnuts to deodorant to breath mints, as The Washington Post reported in 2015. In the process, innocent people have spent months in jail and even pleaded guilty under pressure, The Post reported.

Werts, a redshirt junior who set passing records at GSU last year, had left his grandmother’s apartment in Clinton, South Carolina, for the nearly three-hour drive back to the college in Statesboro, Georgia, when he was pulled over just after 9 p.m. last month. According to a police report, he was clocked traveling at 80 mph and didn’t immediately stop for officers.

Werts later told officers he didn’t feel safe pulling over on a dark, remote road and had called 911 to tell them he was trying to make it to the better-lit town of Saluda before stopping.

“I’m not going to pull over in the dark where no one around can see,” he said on the dash-cam video. “You know what’s been going on in the world. No offense to you, but I just didn’t feel comfortable, officer.”

Once he did stop, though, police quickly zeroed in on a “white powder” on the hood of his car, as officers described it in the report. Werts, sounding confused, told police repeatedly that he’d tried to wash off bird poop but had mostly succeeded in smearing it all over the hood.

Police, though, didn’t buy it. “Unless the bird inhaled cocaine,” one officer said, according to footage reviewed by the George-Anne, GSU’s student newspaper.

When an officer suddenly read him his rights and then told him the field kit had tested positive for cocaine, Werts sat in stunned silence.

“I have no reason to lie to you about cocaine,” he said. “I play football, so I don’t do cocaine.”

Later, in handcuffs, he pleaded his case again. “That’s bird poop,” Werts said.

The officer responded, “That’s a lotta bird poop.”

The quarterback replied, “I don’t know what to say.”

Following his arrest, GSU suspended the quarterback for two days. After passing a drug test, he was allowed to return to practice on Sunday, but was still banned from the season-opening game while the case played out.

On Thursday, he was in a meeting with coaches and players when his attorney called with the news that the drug case had been dropped.

“He was happy to hear the news,” attorney W. Townes Jones IV told the Morning News. “He was confident that’s what would ultimately happen.”

Georgia Southern’s second game of the season will be on Saturday, Sept. 7 when it hosts the University of Maine.

In 2016, the New York Times and ProPublica found that field-testing drug kits, which cost about $2 a piece, are wildly inaccurate. False positives can result from officer errors, the weather or poor lighting, and are so common that as many as one in three tests might come back wrong, The Post reported. Warnings from the Justice Department and crime labs about those problems have done little to slow the use of such kits by local police.

Werts still faces a speeding charge in Saluda County. His attorney said the quarterback has no plans to seek an apology from the sheriff’s department over his drug arrest.

“They had a pretty credible basis for pursuing, and ultimately stopping him and that is speeding,” Jones told the Morning News. “Then they didn’t do anything wrong by attempting to collect evidence . . . It tested positive so they were acting within the bounds of the law at the time.”