Australian NFL star Adam Gotsis says he is relieved and ready to focus on his career with the Denver Broncos after prosecutors opted not to pursue rape allegations against him.

A woman accused Melbourne-born Gotsis, who stands 191cm tall and weighs 139kg, of raping her five years ago after they met at a party in Atlanta, Georgia.

Fulton County District Attorney Paul Howard Jr embarked on a five month investigation after the woman came forward on February 1 this year.

The prosecutor announced on Wednesday "the evidence presented does not warrant any further action".

If charges were laid, Gotsis' NFL career could have ended and if he was convicted he would have likely faced a hefty jail sentence.

"I'm just glad it is over with and I can focus on football now," Gotsis said after a Broncos' practice session.

"You don't really know what's happening, but you just have faith things are going to work out and I'm just glad to be out here with the guys running around.

"There's no place I would rather be."

Gotsis was studying at Georgia Tech and was a member of the university's football team at the time of the 2013 rape allegation.

Gotsis had a brief taste of the Georgia jail system in March when he had to turn himself in to Atlanta's Fulton County Jail in Atlanta.

"I'm just relieved that everything has been taken care of," Gotsis said.

"I've got faith in the legal system and faith in the Lord and family and friends and great support from everyone around me."

The matter echoes a rape allegation made by a woman against NRL star Jarryd Hayne while he was playing in the NFL for the San Francisco 49ers in 2015.

The woman claims she met Hayne at a bar with mutual friends after a 49ers game, she became heavily intoxicated and Hayne raped her at his apartment.

The woman waited five months to go to San Jose police who, after an investigation, decided not to charge Hayne.

The woman has since filed a civil lawsuit against Hayne.

Mr Howard said the decision not to charge Gotsis came "after a careful and thorough investigation".

"My office understands the sensitivity and significance of these investigations, but the evidence presented does not warrant any further action in this case," the prosecutor said.

The Broncos selected Gotisis in the second round of the 2016 NFL draft - the highest pick for an Australian by an NFL team.