Jurors will have to deliver an all-or-nothing verdict on Mikail Markhasev's guilt or innocence in the killing of Ennis Cosby, despite defense pleas for the option of a lesser charge.

Superior Court Judge David Perez refused Thursday to give jurors the option of finding Mark-hasev guilty of second-degree murder, a lesser offense that carries a maximum term of 30 years to life with a chance of parole.Markhasev, 19, is charged with killing the son of entertainer Bill Cosby during a robbery - a felony murder count that makes him eligible for a sentence of life without the possibility of parole if he is convicted.

The defendant is accused of shooting Cosby, 27, as he changed a flat tire along a dark road early on Jan. 16, 1997.

The defense rested its case Thursday with public defender Henry Hall arguing that evidence of attempted robbery to support a felony murder charge "is so thin as to be transparent."

Prosecutor Anne Ingalls said the defendant's jailhouse letters, including a reference to "a robbery gone bad," offers "a great deal of support for attempted robbery."

"So our felony murder theory is safe," she said.

Closing arguments are expected Monday.