A District man on Friday admitted in court to kidnapping and sexually assaulting a woman he saw as she walked in downtown Washington in May.

Saul Castillo, 20, pleaded guilty to second-degree abuse in an attack early May 7. Prosecutors say Castillo did not know the woman who he noticed near Lafayette Square as she seemed to be stumbling on a sidewalk.

When he talked to her, prosecutors said, she said she was trying to go home. They said he hailed a cab and took her to his apartment complex in the 1700 block of Seventh Street NW, prosecutors say.

In the building, she tried to fight him off, but he sexually assaulted her in a staircase, prosecutors said. They said the area was monitored by surveillance cameras.

Castillo is schedule to be sentenced on Nov. 3 by D.C. Superior Court Judge Judith Bartnoff. Upon completing his sentence, Castillo will face deportation to Mexico, authorities said.