It was not immediately known if Nelson, who remains jailed, had retained a lawyer.
Richard said investigators had found the assistant's car stolen from the church parking lot after the attack. She said the car was not located at the apartment complex but would not say where authorities found it, saying the release of that information could jeopardize the case.
Police continue to investigate and have not ruled out the possibility of other suspects, Richard said.
Nelson was convicted of aggravated assault with a deadly weapon in October in Dallas and was sentenced to eight years of probation, according to public records. Then in November he was sent to a state facility that houses defendants who violate their parole, community or mandatory supervision conditions -- and was released less than two weeks ago, according to Texas Department of Criminal Justice records.
Since 2005, Nelson has served some jail time for convictions of property theft, burglary and unauthorized use of a vehicle in the Dallas and Fort Worth area, records show.
Meanwhile, a makeshift memorial of flowers was growing outside the doors of NorthPointe, where Sunday services were being held as scheduled.
Dobson, 28, had led the satellite church of First Baptist Church of Arlington for about three years.