YOUNGSTOWN, Ohio -- The jury that will decide whether an 18-year-old man is responsible for Youngstown's worst mass murder could be selected by the end of the week, the judge said yesterday.

Twelve jurors and two alternates will hear the state's case against Michael Davis, who is charged with starting a house fire on Jan. 23 that killed four small children, their mother and grandmother. Five other people escaped from the house.

Mr. Davis, so boyish that he looks as if he could still be in junior high school, sat impassively as his lawyers and prosecutors questioned prospective jurors.

Prosecutors will ask jurors to impose a death sentence on Mr. Davis if they convict him of aggravated murder and aggravated arson. The state yesterday used one of its peremptory challenges to dismiss a man who said he opposed capital punishment.

Many prospective jurors said they knew little about the case, despite extensive publicity about the six deaths and Mr. Davis' arrest.

Mr. Davis lived two blocks from the victims on Youngstown's East Side. Prosecutors allege that he set their porch on fire, causing the 83-year-old house to quickly go up in flames. Fire investigators said the arsonist fed the fire with gasoline or something similar.

Killed were Carol Crawford, 46; her daughter, Jennifer R. Crawford, 23; and Jennifer's children, Ranaisha, 8; Jeannine, 5; Aleisha, 3; and Brandon, 2.

In court filings, prosecutors allege that rage motived Mr. Davis. They say he targeted the house because he believed someone who lived there stole his cell phone.