ST. PAUL, Minn. (AP) - Authorities have charged a second suspect in the fatal robbery of a young mother who interrupted a burglary at her apartment in St. Paul.

The Ramsey County attorney's office charged 26-year-old Isiah Lee Harper, of Minneapolis, on Friday with first-degree aggravated robbery and first-degree burglary. The complaint says he was present at the burglary last Sunday that led to the death of 24-year-old Sarah Wierstad.

Prosecutors charged 24-year-old Alvin Rudolph Bell, of St. Paul, with second-degree murder on Thursday.

According to the charges, Bell shot Wierstad and later used her credit card to buy gas. A complaint says Harper told police the home was selected at random and he didn't think anyone would get killed.

Wierstad had a 5-year-old girl, worked two jobs and was training to be a chef.