A mistrial was declared Thursday after a jury deadlocked in the case of a former Redskins player accused of felony drunk driving in Fairfax County.

Rickie Harris, 68, an ex-kick returner, could be tried again for allegedly driving under the influence as he returned to his then-Fairfax home from an autograph-signing event in December 2010. He has been convicted of drunk driving two times in the past five years.

The trial generated interest because Harris’s attorney, John Keats, argued that his client’s erratic driving could be blamed on his dementia, which Harris believes may have been induced by hits he took in the NFL. The long-term impacts of on-field concussions are one of the hottest issues in sports today.

“It is anything but a cut and dry DUI case,” Keats said in his opening statement.

Assistant Commonwealth’s Attorney Laura Riddlebarger argued Harris’s mental state was beside the point.

“Dementia does not mean he is not responsible for his actions,” Riddlebarger said in her closing argument. “He chose to drink. He chose to get into the car and he chose to drive.”

Family members testified recent years had been hard for Harris, who played for the Redskins from 1965 to 1970. He was working as a security guard and had started drinking again after a being sober for 17 years. His memory was fading and he could no longer handle his finances.

His ex-wife, Pamela Harris, testified that Rickie Harris took his young granddaughter to the mall one day, but couldn’t find his car when he was leaving. Harris and the girl had to be driven home by a police officer.

“I’m concerned even when he goes out and takes a walk,” Pamela Harris said.

At the beginning of the trial, Fairfax County Circuit Court Judge Michael F. Devine asked Harris a simple question: How old are you?

Harris scrunched up his face as if doing a hard math problem, stammered and then offered up the wrong answer — 67.

Pyschologist Anita Boss testified that Harris suffers from dementia and it could have caused him mental distress that would have led him to weave his car over the center line on Route 50 in Chantilly the night he was arrested.

She also said Harris told her he had discussed his memory problems with old football buddies, who had similar issues. They had a term for it.

“He and his old friends would say they suffered from ‘Can’t remember [expletive]’’ Boss testified. “They called it CRS.”

Harris played in an era of thinly padded helmets and at a bruising position. Nearly two dozen ex-NFL players sued the league last month claiming they have long-term neurological problems as a result of concussions suffered during their playing days. Autopsies on the brains of some ex-players have found they suffered from an Alzheimer’s-like disease, called CTE. It is believed to be caused by repetitive concussions.

Fairfax County police officer Chris Walczyk testified he pulled Harris over around 2:30 a.m. on Dec. 12, 2010 because Harris repeatedly crossed the center line and was speeding on Route 50 in Chantilly.

Walczyk said Harris’s car smelled of alcohol, the driver’s eyes were bloodshot and Harris was unsteady on his feet when he got out of the vehicle.

Harris initially told the officer he had two glasses of champagne that night, but later said it was two glasses of beer, Walczyk testified.

Harris was arrested and taken to the Fairfax County jail, where a breath test showed he had a blood alcohol level of .08, the legal limit in Virginia, according to testimony.

Judge Devine instructed the jury the dementia testimony could only be considered in regards to the manner in which Harris drove on the night in question, not his guilt or innocence on the drunk driving charge.

A juror interviewed after the trial said the jury was 11-to-1 in favor of convicting Harris. The woman, who declined to give her name, said she held out for a not guilty verdict because the defense raised doubts about the breath test machine used in Harris’s case.

A defense expert testified the results of the breath test were suspect because the machine was not recalibrated after some routine maintenance. A prosecution expert testified she thought the machine was in working order.

“They couldn’t lock down whether his blood alcohol level was .08 when he was stopped,” the juror said.

Prosecutors will now have to decide whether to mount another trial against Harris. The defense has asked the charge be dismissed.

If Harris is tried again and convicted, he could face a maximum sentence of five years in jail because it would be his third drunk-driving offense in five years.