Dealers who provide illegal drugs that lead to death would see an increase in penalties under a bill proposed by Massachusetts Gov. Charlie Baker and backed by local law enforcement officials.

"When illegal drug distribution causes a death, laws that were designed to punish the act are inadequate to recognize the seriousness of the resulting harm," Baker wrote in a letter he sent to the state Legislature.

"This legislation would provide for a penalty of up to life in prison and, like the offense of manslaughter while driving drunk, would also require a mandatory minimum sentence of at least five years," he added, pointing to the state's ongoing heroin and opioid epidemic.

There isn't a current state statute that specifically touches on distribution of drugs that result in death.

Baker's bill also calls for family members of witnesses, court staffers and law enforcement officials to receive explicit protections before, during and after a trial.

"Witnesses and other participants in the justice system deserve protection not just during criminal investigations and trials, but also when they return to their communities. This legislation rewrites our witness intimidation statute so that it once again covers retaliatory conduct," Baker wrote in his letter, which is attached to the proposed legislation.

Baker said between 1970 and 2006, witnesses were protected from retaliatory conduct after testifying or cooperating with police because intimidation of a witness was a felony. But a 2006 rewrite, aimed at reducing gang violence, led to the state's highest court to rule that the law didn't cover retaliatory conduct.

"Therefore, in 2011, the [Supreme Judicial Court] ruled that a person who threatened to harm the daughter of his probation officer in retaliation for his supervision could not be convicted of this felony offense," Baker wrote. "While this may not be the result the Legislature intended in 2006, it remains the law of the Commonwealth today."

Another component of the proposed bill updates the "murder for hire" penalties.

"The lack of an appropriate punishment under our law, which punishes solicitation to commit murder as a misdemeanor, has led to Massachusetts authorities requesting federal assistance in cases where a person has solicited someone to commit murder for hire in Massachusetts," Baker's letter says.

The bill also links federal classification of new lethal drugs to state-level drug classifications, but state officials keep their authority to make final decisions about how to treat new drugs.

"Under our current system, when a dangerous new drug appears on the scene, the federal government moves quickly to employ its emergency scheduling powers to make sure that federal law prohibits the importation and sale of these lethal drugs," Baker's public safety chief, Dan Bennett, said in a statement. "If state laws lag behind it makes sense to adopt federal scheduling, as other states have, to ensure police can take action when they encounter lethal new drugs out on the streets."

Baker was set to formally unveil the bill in South Boston at the Gavin Foundation's Devine Recovery Center.

According to the Baker administration, the bill is backed by the Massachusetts District Attorneys Association, Massachusetts Major City Police Chiefs Association and the Massachusetts Chiefs of Police Association.