SPRING, TX --Homicide investigators are now involved in an almost month-long search for a missing Spring teen they originally classified as a runaway. Alexandria Lowitzer, 16, was last seen getting off her school bus just a few feet from her Spring home on April 26. The girl, whom family members describe as an avid text message user and Girl Scout, hasn't contacted anyone since her disappearance, according to Friendswood-based search group the Laura Recovery Center for Missing Children. The Harris County Sheriff's Office had classified Lowitzer as a runaway. However, the Laura Recovery Center, which says it doesn't assist in searches for runaways, decided to get involved because Lowitzer's family members and friends claim it's unlikely for the teen to just run away. Volunteers have searched extensively in the woods behind her home and found nothing. Amid the growing concerns in the community, the sheriff's department decided to assign homicide investigators to help officials in the missing persons division find the teen. Meanwhile, The Laura Recovery Center for Missing Children is planning another ground search for the teen this weekend. Volunteers are asked to meet at 9am Saturday and Sunday in the parking lot of the Northwood Baptist Church, 5803 Treaschwig Road, Spring, Texas. The searches are expected to last until 4pm. Individuals interested in volunteering must have a valid driver's license, be at least 18 years old and are encouraged to wear clothes that can handle rugged terrain.