(Oklahoma City-AP) -- It's been a year since the body of Margaret Gardner was found near an entrance ramp to Interstate 40 close to the Arkansas-Tennessee stateline.
A blow to the head killed Gardner, who had worked as a prostitute at truck stops. Her partially nude body was found July Eleventh.
Gardner's death was the first in a string of more than ten prostitute slayings that investigators have linked together.
A year later, law enforcement officials from Pennsylvania to Arizona still search for clues that might link a suspect or suspects to the brutal murders.
Earlier this month, more than 20 law enforcement officials from seven states met in Grapevine, to discuss the murders.
Police in the Dallas suburb are investigating the death of 19-year-old Casey Pipestem, whose body was found there January 31st.
Pipestem, tall and athletic, was known to have worked as a prostitute at Oklahoma City truck stops.
Victims in a multi-state investigation into slayings of prostitutes:
_Vesta B. Meadows, last seen alive at a truck stop in Knoxville, Tenn. Her body was found June 11, west of Harrisburg, Penn., along the Pennsylvania Turnpike.
_Buffie Brawley, 27, last seen at a Flying J truck stop on the southside of Indianapolis on March 23. She was found March 24 at an abandoned truck stop along Interstate 74. She had been bound, strangled, beaten and run over.
_ Casey Jo Pipestem, 19, of Shawnee. Last seen at an Oklahoma City truck stop, found nude near Big Bear Creek off Texas 360 in Grapevine on Jan. 31. Pipestem was strangled.
_ Patsy Laverne Leonard, 23, a prostitute last seen in Wichita Falls, Texas. She was found nude and strangled Jan. 1 in a creek in northeast Pottawatomie County, Okla.
_ Sandra Richardson, 39, of Oklahoma City, was found at the junction of Highways 62 and 48 in Okfuskee County east of Oklahoma City on Nov. 22. OSBI reports she died from physical trauma. The body was unclothed.
_ An unidentified woman last seen at the Flying J Travel Plaza in Sayre, Okla., trying to hitch a ride. Her body was found off Interstate 40 in Texas, 45 miles west of the Oklahoma border on Oct. 16. Cause of death not released.
_ Sandra Beard, also known as Sandra Bates, age 43, of Oklahoma City, found along I-40 at the Tiger Mountain Road exit in McIntosh County, Okla. She was a prostitute. She died of asphyxiation and was found nude Sept. 18.
_ Jennifer Hyman, 24, of Oklahoma City, last seen at an Oklahoma City truck stop. Hyman, a prostitute, was found nude and strangled, below a Tallahatchie River bridge near Oxford, Miss., on Aug. 20.
_ Margaret Gardner of Memphis, Tenn., last seen at an Arkansas truck stop. She was found partially nude on an entrance ramp to I-40 near West Memphis, Ark., on July 11, 2003. She was killed by a blow to the head.