A man with a long record of drug crimes and violent offenses allegedly spent a half-hour rummaging through an unconscious man’s belongings, stole a prescription drug and “multiple’’ other items, and left the man to die alone on a subway platform in Boston early Wednesday, according to the Suffolk district attorney’s office.

Anthony Stimson, 30, of Boston faces charges of larceny and possession of a Class E drug after he allegedly took the nerve pain drug gabapentin and other possessions from 52-year-old Willie Williams as Williams lay on the southbound Red Line platform at Downtown Crossing, according to court filings.

Superintendent Richard Sullivan, a spokesman for the MBTA Transit Police, expressed revulsion at the callous nature of the crime.

“In my 20-plus years, I can only recall this happening one other time,’’ he said, going on to cite the 2014 case when Josue Gonzalez of Brockton allegedly stole the cellphone of a woman struck and killed by a Red Line train at the same MBTA station.

“I view this as along the same line of depravity,’’ Sullivan said, adding that Stimson is “known to the T police. We’ve had dealings and encounters with him in the past, including this year.’’

For both Williams and Stimson, the address listed in court filings is the Pine Street Inn, a South End homeless shelter.

Barbara Trevisan, a shelter spokeswoman, said privacy laws prevented her from confirming whether the men had lived there. She added that homeless people in Boston often will give the shelter’s address as their own, whether they currently reside there or not.

Speaking at Stimson’s arraignment in Boston Municipal Court on Wednesday, his attorney, Patrick J. Colvario, said his client has a “substance abuse problem’’ and that Williams’s death “is a sad circumstance; it’s a sad fact of this case.’’

Colvario did not deny that pills prescribed to Williams were found in Stimson’s possession but suggested that someone else could have taken the pills from Williams and passed them to Stimson.

Stimson has a nine-page record of criminal charges and convictions in Massachusetts and Texas that stretches back to at least 2005 and includes a restraining order, several stints of incarceration, and probation violations, Alyssa Tochka, a Suffolk assistant district attorney, said at the arraignment.

He faces current charges for other crimes that include larceny, drug possession, and drug possession with the intent to distribute, Tochka said.

Justice Richard J. Sinnott revoked Stimson’s bail in those cases. Stimson pleaded not guilty and was held on $10,000 cash bail. He is scheduled to return to court April 19 for a pre-trial hearing.

Surveillance video of the T station shows that Williams entered the station shortly before 3:30 a.m. Wednesday and that within a few minutes appeared “to be having difficulty breathing and to be in medical distress,’’ Tochka said in court.

Stimson arrived on the platform nine minutes later, took a bag that was near where Williams lay on a bench, walked away to sort through its contents, then returned and searched through Williams’s pockets and suitcases as he lay dying, Tochka said.

Stimson “made no effort to render aid or reach out for help for Williams,’’ Transit Police said in the arrest report. After Stimson allegedly completed his search, taking the prescription drug, two bottles of Suave shampoo, and other items, he left the station, according to the report.

Transit Police officers were summoned to the platform just after 5 a.m. to find Williams unconscious there, the report says.

Officers attempted to revive Williams and summoned Boston Emergency Medical Services, but their combined efforts were unsuccessful, Transit Police said. EMS pronounced Williams dead at the scene at 5:13 a.m.

Officers soon found Stimson outside the 7-Eleven on Summer Street downtown, detained him, and searched him, finding a metal hammer in the back right pocket of his jeans and the pills in a orange bottle with Williams’s name on the prescription label, according to the report.

Stimson waived his Miranda rights and told officers he and Williams were acquainted, Transit Police said.

“Yeah, I know that guy. He dated my mother. It’s not a big deal,’’ Stimson allegedly told the officers. He also allegedly admitted stealing from Williams. “Yeah, I took his shampoo. It’s worth like $2.’’

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.