A family member of the fitness instructor killed last week in a North Texas church, apparently by someone in a SWAT team uniform, asked the killer to come forward Sunday and “give some honor back to your family.”

Terri "Missy" Bevers, 45, of Red Oak, was found last Monday by a student arriving for a class, police said.

Bevers, a married mother of three, was killed at Creekside Church of Christ in Midlothian, 20 miles southwest of Dallas.

CBS Dallas reported that Bevers, who was preparing for a 5 a.m. boot camp class, died from a head wound. Authorities said the killer used an unidentified blunt object to strike her.

Marsha Essary Tucker, the victim’s mother-in-law, posted a message on Facebook Sunday touching on the toll the killing took on her family. But she also said the crime would also hurt the killer's own relatives.

“You have now ruined your children’s life, along with your family’s life by doing this senseless act,” Tucker wrote. “We can at least visit Missy’s gravesite, even though we have the comfort of knowing she is already in heaven. Your family will get to visit you in prison, forever reminded of your crazy, selfish act. What a legacy you have doled out to your family.”

Surveillance video shows the suspect inside the church minutes before the fitness instructor arrived. Investigators say the killer wore a jacket labeled "Police," gloves and a helmet. In fact, the suspect wore so much clothing, even determining his or her gender has proved challenging.

Police found broken glass on the floor and evidence of forced entry into the church, possibly for a burglary.

The Associated Press contributed to this report