Adopted Ohio Man Searching for Biological Family Discovers an Unexpected History of Violence

Anthony Allen's story will be told on Monday night in the latest episode of TLC's Long Lost Family

Imagine learning as an adult that you may have had two twin brothers and that one of them was killed in a homicide — as an infant.

That’s what happened to Anthony Allen, an Ohio man whose story will be told on Monday night in the latest episode of TLC’s Long Lost Family, which follows people reunited with their biological relatives.

In an exclusive preview of the episode, Allen details how he first learned at 10 years old that he was adopted and how he began looking into what happened to his biological family years later, when his adoption records became available.

“I had a wonderful childhood, but I grew up alone, I was the only child. I never really had anybody to talk to,” Allen says, noting that he “always wanted a sibling, especially a brother.”

“The older I got, the more inquisitive I became,” he says.

As Allen discovered in recent years, records and newspaper articles led him to believe he had two older brothers — twins — named David and Paul. The latter boy was killed at 6 months old by Frank Newell, described as his father, when he wouldn’t stop crying in his crib, Allen’s investigation showed.

Allen says his biological mother was pregnant with him at the time.

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PEOPLE was unable to confirm if Newell was ever charged in connection with Paul’s death. He died in Kentucky in 2005, at age 67, according to federal records.

“I was shocked, I was angry, I was kind of embarrassed that I had a murderer in my family,” Allen says. “It’s just heartbreaking.”

In the clip, Allen describes growing up alone in Middletown, Ohio, longing for a brother; and he says now that he deals with guilt for having a “very good life … and Paul was taken at such a young age.”

As his search continues for the other twin, David, and for what really became of his biological family, Allen says Paul’s remains have been buried in the Middletown area.

Tearing up, he says, “We decided that we should honor Paul and put a head-marker on there so that he would not be forgotten.”

TLC describes the series as telling “the highly emotional and touching stories of people who have suffered a lifetime of separation and are yearning to be reunited with family members, whether it’s children, parents, siblings, or those they never expected.”

Long Lost Family airs Monday (8 p.m. ET) on TLC.