RIVERHEAD, N.Y. — The last of seven New York teenagers implicated in the hate crime killing of an Ecuadorean immigrant has pleaded guilty.

Anthony Hartford’s plea Wednesday to gang assault and other charges closes the prosecution phase of a case that attracted international headlines. It prompted an ongoing U.S. Justice Department probe of police responses to bias crimes.

The 18-year-old admitted being with a group that targeted Hispanics for violence in November 2008. Their attacks culminated in the killing of immigrant Marcelo Lucero (mar-SEHL’-oh loo-SEHR’-oh) in Patchogue (PACH’-awg).

A week ago, 19-year-old Jeffrey Conroy was sentenced to 25 years in prison. He was convicted of manslaughter as a hate crime.

Five others are awaiting sentencing.