He was accused by former personal trainer Brian McNamee in the Mitchell Report on drugs in baseball of using steroids and HGH, allegations Clemens denied before Congress. The Justice Department began an investigation into whether he had lied under oath, and in 2010 a grand jury indicted him on two counts of perjury, three counts of making false statements and one count of obstructing Congress.

He was acquitted of all the charges on June 19 after a 10-week trial and had largely stayed out of the public spotlight until now.

Many of his former teammates have said they believe that he could pitch again in the majors.

Clemens had two great seasons with the Astros after he turned 40, going 18-4 with a 2.98 ERA in 2004 to win his record seventh Cy Young Award. He was 13-8 with a career-low 1.87 ERA in 2005 while helping his hometown Astros reach their only World Series, and the team has already said it wouldn't rule out bringing him back this year.