Former San Quentin inmate making the most of a new starting line in life

SAN FRANCISCO (CBS SF) -- They say you can't outrun your past, but Markelle Taylor knows you can built a new future one stride at a time.

Taylor served nearly 18 years in San Quentin State Prison for the assault of his pregnant girlfriend that resulted in the death of the couple's unborn child.

It was during those long days behind the prison walls that Taylor began to turn his life around. He did it one stride at a time on the dusty, makeshift running track on the prison yard as a member of San Quentin's unique 1,000 Mile Running Club.

His speed earned him a nickname -- 'Markelle the Gazelle' -- and his story will soon be the subject of a documentary.

The dusty track has been replaced by daily training runs along the San Francisco waterfront. It's something, the 49-year-old says he once could only dream of.

"I didn't think I would never get out (of prison)," he told CBS News.

While Taylor says there are no excuses for what he did, he did grow up in an abusive household.

"We would get abused if the dishes ain't washed, or if the house ain't clean, or if it ain't clean to their specifications, then we would get whooped out of our sleep," he said.

Taylor honed his running skills during monthly races that the volunteer coaching staff stage at the prison. 

"I won every one of 'em except for one," he said with a grin.

He said he races gave him an emotional high.

"It was also because when I ran, I ran to honor my son," he said. "And-- it was like that, you know what? You made a mistake, but keep running. We have faith in you to be a better person."

One of those volunteer coaches -- Diana Fitzpatrick -- still works with Taylor.

"You have a choice when you end up at a place like San Quentin," she said. "And you can just lay around and let the time go by and wait for something to happen. Or you can take control of your life and try to do something with it. And Markelle's someone who really chose to do something with his life."

While in San Quentin, Taylor ran a makeshift marathon so fast, he qualified for the 2019 Boston Marathon. A month before the race he was released on parole.

"I couldn't really enjoy Boston because I was still, you know, bein' happy and appreciative of just bein' free," he said of the 2019 race.

This spring he was back in Boston again and his time of 16:02:25 was among the top 5% of the finishers. Now, he's preparing for the Chicago Marathon.

"I feel like I signed a pledge of being nonviolent," he said. "And I know that -- not only do I owe it to myself and the people who I victimized in my lifetime, I owe it to all those who are counting on me and people who are looking for me to be a positive influence in their life."