Anthony Riley speaks about his 'Voice' departure

Philly street performer Anthony Riley made history on

The Voice

when he received the TV show's fastest four-chair turn-around ever from the judges after an impassioned performance of James Brown's "I Got You (I Feel Good)."

But on Monday's show, judge Pharrell Williams announced that Riley had left The Voice for personal reasons. Philly.com reported that Riley's departure was due to substance-abuse issues.

Now, Riley is opening up about the problems that have plagued him. The 28-year-old said he struggled with drug addiction for two years, but since leaving The Voice has completed a rehabilitation program. "For me it's tough, because everyone's just finding out and I've been moving forward" past my departure, he said from Pittsburgh.

Riley sat down with The Voice's production staff in January after his first Battle Round victory and shared his ongoing struggle with substance abuse. That night, NBC producers flew him out from Los Angeles, where The Voice is shot, back to Philadelphia so he could enter Clarity Way, a drug and alcohol rehab facility in Hanover, Pa.

Riley said NBC footed the bill. NBC did not return a request for comment.

"The Voice has been a really great source of support," Riley said. "At the time, [being on the show] wasn't working for me and I felt like I needed to go, instead of taking on more responsibility than I could handle."

During that time, he said, he was working 14 to 16 hour days.

"They made sure we understood what we were getting ourselves into," Riley said. "It's stressful; there are a lot of days that can turn into lonely days."

Lonely days aren't good for someone dealing with depression, mental-health issues or substance abuse, he said. "I had a lot of time to think about myself. I recognized something was getting the best of me."

Riley told NBC that he'd like to be a part of Season 9, but for now, he said, "The Voice is over for me."

Riley said he is speaking out because he wants to clear up the rumors surrounding his departure, such as fear of competing against fellow contestant Mia Z in a Battle Round. Riley said Mia Z is "quite literally one of the best singers I've heard in my life. If anything, it would be an honor to go up against her."

Riley also said he did not send out a controversial tweet from his account dedicating a performance to Mumia Abu-Jamal, including a video of a 2013 rally in Philadelphia in support of the convicted cop-killer.

"I don't think entertainment and politics should intersect," Riley said. "I literally want my fans to get to know me through my music before we delve into political associations and affiliations."

The tweet was sent by Christopher Mapp, Riley's former assistant. Mapp said he has been unfairly referred to as a "disgruntled manager," and that the tweet "wasn't malicious."

"I shot the video," Mapp said about the attached media. "I supported the cause."

Mapp, who said he personally witnessed Riley's drug use, also claimed he was nearly evicted due to some of Riley's choices. Mapp said he and countless others have shelled out money for Riley without reimbursement.

"He needs help," Mapp said.

Riley said he's rebuilding his career while continuing outpatient treatment and therapy. He plans to return to Philadelphia.

Riley said he's now committed to his sobriety and mental and spiritual health. He said he feels blessed and plans on sharing his story through music as he writes his first album.

"One of the reasons I'm proud of being of a Philadelphian is that we all have our own struggle, no matter what you do, no matter how far down you go, you can always make a comeback," he said. "I just hope someone hears this message. It's not worth pursuing anything other than your dreams."