The family of a Maryland man missing for three weeks says he’s been found dead. Now they’ve got to get police to agree with them.

Ali Khadar disappeared from Brentwood, Md., on April 26. His sister, Zainab Khadar, says a body Prince George’s County Police found near a creek on Sunday is his.

Authorities, though, say they can’t confirm that. PGPD spokesperson Corporal Mike Rodriguez says a body was found in a Laurel County swamp on Sunday, but officials haven’t been able to positively identify the body as Khadar’s. “We can’t scientifically say it’s him,” says Rodriguez.

Asked about the police department’s doubts, Zainab Khadar explains that the family knows the corpse is Ali Khadar. Her father went to see it and was able to spot a distinctive tattoo his son has of a diabetic shield. But police, she says, insist on identifying him through his dental records. She believes her brother’s death was foul play.

“He was in bed and he got a phone call and he got up and he didn’t come home,” says Zainab Khadar. She points out that her 27-year-old sibling was on the verge of graduating from Strayer University and “wasn’t into anything bad. But “this kid that he would give rides to was bad news.”

She says cell phone records indicate the “kid” was the last person her brother spoke to. “We’ve been trying to tell the detectives that they need to investigate this kid, but they’re not very responsive.”

Zainab Khadar says her brother would have turned 28 last Friday, and had landed an interview for an IT job.