Philadelphia (CNN) -- Robert Sanabria thought he would never see his big brother again.
Robert was 15 when his brother, Edwin, left home at age 18.
Born prematurely with only one functioning lung, Edwin spent his school years in special education classes, Robert said. He remembered his brother as soft-spoken, humble and kindhearted.
"When he left, he just took off," Robert told CNN by phone last Saturday. "He was in love and ran away."
He last saw his brother in 1999. Neighbors and friends would tell Robert they thought they spotted Edwin around the city.
"It was like a bigfoot sighting," he said. "Every time they said they saw him it went nowhere. The information led to a dead end."
Robert, 29, is a sergeant in the U.S. Army who lives with his wife outside Fort Bragg, North Carolina.
All his years of military training and combat experience couldn't prepare him for what happened a few weeks ago.
In mid-October, Robert received a call from his father, who told him police might have found Edwin locked in a dank Philadelphia basement with three other people.
The pitch-black, 15-by-6-foot space discovered by the owner of the apartment building houses what police described as an abandoned boiler room, where the overwhelming stench of urine and feces still hung in the chamber two days after the discovery.
Hours after his father's phone call, Robert made the nine-hour drive north to see if his long-lost brother was among the four victims.
"It made me nauseous. I was anxious. It was eating me up. I was crying on the way up there. If that gut feeling wasn't there, I wouldn't have gone," he said. "We still didn't know if it was him, but there was only one way to find out."
Media reports identified Edwin Sanabria and Tamara Breeden as two of the victims.
"When I saw their names together, I knew it was my brother and his girlfriend. I couldn't believe it," Robert said.
When Edwin left his Philadelphia home at 18, he told Robert he was staying with his girlfriend, Tamara, and her family, Robert said.
"They were in love. We were hoping that they were being taken care of," Robert said.
After Edwin lost contact with his family, the Sanabrias asked for help in tracking him down from Philadelphia police and the local Social Security Administration office, which distributed disability benefits checks to Edwin.
Their efforts were in vain. Edwin was an adult who left home on his own, so the police couldn't intervene. Access to Edwin's personal information from the Social Security Administration wasn't possible because it was considered a violation of his privacy, Robert said.
It would take more than a decade for the Sanabrias to discover Edwin's fate. Robert said it was Breeden who introduced Edwin to one of his alleged captors, and he believes his brother's abuse could have started soon after Edwin left home. Police have not said how long Edwin may have been captive.
Last month in Philadelphia, Robert and his father met with police and were sent to a health care facility where the captives were being evaluated.
Expecting a hug and ceremonious reunion, Robert was greeted with a nonchalant head nod. Exhausted and feeling defeated, he began to cry, fearing his brother no longer even recognized him, he said.
But as if on cue, Edwin stood up and walked over to the stunned men and said, "Pop," to his father.
Robert, a self-described tough guy who completed two tours in Iraq, wept uncontrollably.
"I am bawling. I realized how much I missed him, how much I loved him," he said. "He looked really, really skinny and really malnourished."
Then Edwin started looking closer at his crying brother and said, "Robert?"
He quickly flashed Edwin his military ID. Edwin held it inches from his face, almost straining to read it, Robert said. Edwin started talking, and then wrapped his lanky arms around his baby brother.
"He gave me a long hug," Robert said. "Then he said, 'You know what I want? I want a cheesesteak.' So I went and got him one as fast as I could."
Police arrested Linda Ann Weston, 51, Gregory Thomas, 47, Eddie Wright, 49, and Weston's daughter, Jean McIntosh, 32, for allegedly imprisoning four mentally disabled adults in the basement boiler room. They face a host of charges including criminal conspiracy, aggravated assault, kidnapping, criminal trespass, unlawful restraint and false imprisonment.
Weston, Wright and McIntosh face additional charges -- including aggravated assault, simple assault, kidnapping and reckless endangerment -- in connection with the alleged abuse of Weston's niece, Beatrice Weston, authorities said.
A hearing for the new charges is set for November 15. All four suspects in the case are scheduled to appear in court on December 19.
Weston had identification documents for about 50 people with her when she was arrested, Philadelphia Police Commissioner Charles Ramsey said. Those documents included Social Security cards and court documents giving power of attorney. Police said they were investigating whether the victims' Social Security checks had been stolen, as well as several other leads.
In addition to the four captives found in the basement, authorities have located 10 other potential victims, including six children, Ramsey said.
Police believe two of the six children placed in protective custody -- ages 2 and 5 -- are the children of Tamara Breeden. DNA testing is being conducted to confirm paternity, but the Sanabrias believe Edwin is the father.
Edwin is slowly opening up about his ordeal, Robert said. Edwin never fled because he loved Breeden and he was never left alone, he said. He also said he was mistreated by Weston's teenage sons.
Edwin said he would often fight back and share his food with the others while he was with Weston, Robert said. Edwin said he would also intercept blows intended for Breeden. Edwin also recalled separate incidents in which he was sliced with a knife and shot with a BB gun, Robert said.
Edwin told his brother that one of the captives, Herbert Knowles, had seizures in the basement, so he gave him water and placed a cold rag on his head, Robert said. He said the water came from the same bucket they used as a toilet and to bathe.
Worried about the physical and emotional abuse his brother endured, Robert said he plans to have Edwin come live with him, and vows to protect him to the end.
"The first thing I wanted to tell him was that this was not his fault, that everybody gets tricked," he said. "It's disturbing. It still messes with me. They (the defendants) all deserve life in prison."