A Mexican Mafia hit man convicted of beating and strangling a San Antonio woman because she didn't pay the gang's 10 percent tax on her illegal drug sales is heading for the Texas death chamber.

The lethal injection of 46-year-old Manuel Vasquez on Wednesday evening would leave Texas with enough of the sedative pentobarbital for only one more execution. At least another six prisoners have execution dates in the coming weeks.

Texas prison officials, like those in other death penalty states, are finding it increasingly difficult to find suppliers to provide drugs for capital punishment use.

Vasquez was convicted in the 1998 slaying of 51-year-old Juanita Ybarra. Testimony at his trial showed Ybarra had ignored the gang's "dime" drug tax, so Vasquez and two partners were ordered to kill her.