Under current law, Indiana judges have the option of sentencing violent offenders using a firearm during a crime to an additional five years in prison.
"We can no longer tolerate home invasions, violent crimes, senseless shootings and murders in our communities," Merritt said in a statement. "I believe we need to strengthen penalties against violent offenders throughout Indiana to keep them off our streets."
Merritt said two home invasions in October on Indianapolis' north side spurred the legislation. In both of those cases, police said groups of armed men broke into homes, terrorized families and stole their cars.
A mother and daughter were sexually assaulted and one of them was shot in one of those home-invasions.
Merritt cited the case of Shamus Patton, who injured eight people when he fired shots into a downtown Indianapolis crowd in 2010 after Indiana Black Expo's Summer Celebration.
Patton served less than three years of an eight-year sentence, and he was arrested again in June when a vehicle he was in led police on a chase, the newspaper reported.
"Shamus Patton is a primary example of why Indiana needs to strengthen its minimum imprisonment penalty for violent offenders," Merritt said. "My hope is we can reduce crime by keeping violent offenders in prison for a longer period of time, and this legislation will give prosecutors and judges the tools needed to put away these individuals so they remain out of Indiana's neighborhoods, schools and homes."
Efforts to toughen Indiana's sentencing laws already are underway. A law passed by the General Assembly last spring requires prisoners to serve at least 75 percent of a sentence, even if the offender has shown perfect behavior behind bars.
That law, which takes effect in July 2104, also caps sentence reductions at two years for completing certain educational or therapy programs. Previously, it was four years. Merritt's proposal could further toughen the new law.
Indianapolis Mayor Greg Ballard, who's been working with Merritt on the measure, would welcome tougher sentences for violent crimes, his spokesman said.
"Approximately 80 percent of the criminal homicide victims and suspects in Marion County in 2013 had criminal backgrounds, including previous weapons charges," said Ballard spokesman Marc Lotter.
Lotter said Ballard wants to increase sentences for people who commit violent crimes, particularly those involving a weapon.