Ingham County Assistant Prosecutor Michael Ferency urged jurors to convict Holland of first-degree felony murder.
"This was not an accident," he said. "This was something that was done purposefully with the kind of mind that would make someone responsible for murder."
Ferency cited injuries Ricky sustained that are consistent with child abuse and said the boy likely died a slow death from a brain injury caused when Lisa Holland struck him with a hammer.
But defense attorney Andrew Abood told jurors that Lisa Holland' husband, Tim, is a liar who cut a deal with prosecutors and wrongly pinned blame on his wife.
"When is it easier to lie than tell the truth?" Abood asked. "The answer is when you've killed your son."
Lisa Holland, of Williamston, is charged with first-degree child abuse and felony murder in Ricky's 2005 death. Tim Holland led police to the body and pleaded guilty to second-degree murder as part of an agreement to testify against his wife.
Tim Holland, 37, has testified that his 33-year-old wife told him she hit Ricky in the head with a small hammer.
Felony murder is punishable by life in prison without parole, while second-degree murder can bring a life sentence or less and the chance for parole. To convict Lisa Holland of felony murder, prosecutors are trying to prove the death occurred while she committed first-degree child abuse.
Ricky vanished from his Williamston home east of Lansing in July 2005. His adoptive parents said he ran away, sparking a nine-day search by 1,700 volunteers and hundreds of law enforcement officers.
Volunteers, dive teams and K-9 units had scoured in ever-widening circles. Through it all, Ricky's adoptive parents told searchers and the media that he'd run away.
Abuse may have marred Ricky's years with the Hollands, who became his foster parents in 2000 and adopted him in 2003. But neglect marked his time with his birth parents, whose rights were terminated in 2002, according to court documents.
Medical examiners classified the death as homicide by unspecified means and found fractures to Ricky's upper body and face.
Jury selection in the trial began Sept. 11.
After closing arguments, Circuit Judge Paula Manderfield instructed the jury, which was expected to begin deliberating as early as Wednesday afternoon.