I came across some info pertaining to this case...
As reported in the Galveston Daily News, March 28 1981, Brazoria County sheriff's dep't investigators, along with Ft. Worth police, were searching a swamp near the town of Alvin for human remains. In 1976, an oil rig worker discovered two skulls and a jaw in the area. But, due to what was termed a "bad search", nothing else was recovered at the time. Due to the election of a new sheriff, several cases were being given a second look. LE believed that the skulls may have had something to do with the disappearance of Trlica, Wilson, and Mosely.
During the search on the 28th, human teeth, vertebrae, two pair of girls' pants and a high school drama book were recovered. The remains were sent to the coroner for dental comparison.
On April 5th, 1981, it was reported that the remains belonged to two girls who had disappeared in 1974 from nearby Dickinson, Texas. Georgia Geer, 14, and Brooks Bracewell, 12, had disappeared without a trace in September while on their way to their school bus stop.
The articles then went on to discuss the possibility that 40 other girls had gone missing and been murdered in the area of Brazoria County and the surrounding counties. By the mid-70's, the bodies of 21 girls who had been reported missing in 1971 and 1972 had been found. In 1974 and 1975, an additional 17 were reported missing. Police had developed a (unnamed) suspect in 1971, who was subsequently killed by police in 1972.
The "official" LE story was that there was nothing substantial to link the cases. Unofficially, detectives were reported to say that there had to be something to it...The girls ranged in age from 12 to 21, most being 14 or 15. Almost all shared the same general physical features; thin builds, long, straight light to medium brown hair parted in the middle.
Almost all were found in or very close to water.
Other articles, dated as late as 2002, compiled missing/recovered/unidentifed victim reports from the area. One report stated that since 1971, 21 girls and women had gone missing along the I-45 corridor through the area, and the LE had recovered the remains of 14. This number includes those found in the Calder Rd "killing field", as discussed in another thread here.