VIRGINIA BEACH, Va. (WAVY) — Two Virginia Beach delegates have written a letter to City Council asking for members to call for an outside investigation into the mass shooting that killed a dozen people and injured others in May.

10 On Your Side obtained a copy of the letter, which was sent to City Council on Monday by Virginia Beach delegates Cheryl B. Turpin and Kelly C. Fowler.

In the letter, Turpin and Fowler wrote that they hope Virginia Beach City Council will “take the lead” in conducting an outside investigation into the “relevant events that occurred before, during and after this mass murder in a government building.”

12 people were killed, and four others critically injured, at the Virginia Beach Municipal Center by gunman DeWayne Craddock on May 31. The 40-year-old suspect was a longtime employee of the city’s Public Utilities Department who resigned from his job on the day of the shooting.

In the aftermath of the shooting, there were reports that first responders weren’t able to access certain parts of the Virginia Beach Municipal Center during the mass shooting because there were issues with the building’s electronic locks. Turpin and Fowler also wrote that they’ve heard concerns of “communication failures and delays” after the mass shooting and complaints that the victim’s family members haven’t received enough information about the city’s investigation into the tragedy, according to the letter.

“This information leads us to conclude that it is necessary and appropriate that City Council take the lead in conducting a comprehensive investigation into the relevant events that occurred before, during and after this mass murder in a government building,” Turpin and Fowler wrote in the letter.

Like Attorney Kevin Martingayle, who is representing the family of one of the mass shooting victims — 42-year-old Katherine Nixon — Turpin and Fowler suggested that Virginia Beach City Council look to Tim Heaphy to conduct the investigation. Heaphy is currently the General Council at the University of Virginia, and conducted an outside investigation into the deadly riot in Charlottesville that happened in August 2017.