The defense tried to cast suspicion on the man whose family perished in the flames, Edit Vanegas.
Vanegas was crying outside court and spoke of the trauma of not being able to rescue his two young girls despite their cries for help.
"He's an evil person," said America Chavez, who is related to the victims.
A few feet away, Lacey's family held an impromptu prayer circle in court insisting that he is innocent. Lacey's father is a preacher.
"He's a person who helps people, who saves peoples lives," said Lacey's brother Leon.
Prosecutors say Lacey poured gasoline on the stairwell of his neighbors' two-story apartment building, and that his plan was to rescue the family.
Defense attorney Chris Cassar told jurors that the evidence against Lacey is weak, and accused Edit Vanegas of having an abusive relationship with his wife.
"This is an individual," Cassar said of Mr. Vanegas, "That had a very violent relationship with his wife at the time, and was the last one in the building, and the first one out."
Mr. Vanegas escaped the fire with his two sons.