Three people were in custody for questioning Monday but none had been charged, authorities said.
The body parts were discovered Sunday, about a mile from where another headless torso was discovered two years ago in a widely publicized case involving New York real estate heir Robert Durst, authorities said. Durst was acquitted of a murder charge last month.
Officials identified the remains found Sunday as belonging to Ranferi Arizaga, 30, of Houston.
Houston police spokeswoman Sandra Aponte said Arizaga had been reported missing a few days earlier, but she said few other details were known yet. Arizaga's arms and legs had not been found, Galveston County sheriff's detective Ray Tuttoilmondo said.
Galveston County Commissioner Eddie Janek, who lives nearby, said he watched Sunday as police retrieved the body, which was wrapped in a plastic bag. He also watched in 2001 as authorities retrieved the body of 71-year-old Morris Black, the man Durst was charged with murdering.
"As clear as it was Sunday, I probably could have seen the suitcase from my porch," Janek told the Houston Chronicle.
Police never recovered Black's head, but the defense and prosecution in Durst's murder trial agreed that Black died from a bullet wound to the head.
Durst testified that Black was shot accidentally while the two struggled over a pistol. He said he panicked and cut up the body to dispose of it.
Durst said he dumped Black's head into the bay near Janek's home along with the other body parts.
Prosecutors said Durst hid Black's head to make sure it would never be available for forensic examination.