New Haven (AP) - A man who served prison time with convicted home invasion murderer Joshua Komisarjevsky before the 2007 killings testified Friday that Komisarjevsky was polite and studious in jail, but "emotionally dead."

Sean Baraby took the witness stand in the penalty phase of Komisarjevsky's trial in New Haven Superior Court. The jury that convicted Komisarjevsky last month of capital felony, murder and sexual assault for killing a woman and her two daughters in Cheshire will be deciding whether he gets the death penalty or life in prison. His co-defendant, Steven Hayes, is already on death row.

Baraby said he served three months in state prison in 2005 with Komisarjevsky, who was locked up for a string of burglaries and later paroled. He said Komisarjevsky took him under his wing and told him which inmates he should avoid.

State's Attorney Michael Dearington questioned Baraby on cross-examination about what he meant by "emotionally dead." Dearington asked if he meant Komisarjevsky was just a calm person and Baraby answered "Yes."

Another witness, Matthew Stachkunas, testified Friday via a live video conference from his hometown of Sarasota, Fla., that he took Komisarjevsky into his home in Southington in 2001 to help him with an unspecified drug addiction as he recovered from an overdose.

Stachkunas said Komisarjevsky was a good house guest who was calm and quiet, but never aggressive.

The defense is trying to convince the jury that Komisarjevsky has redeeming qualities and should be spared the death penalty for the killings of Jennifer Hawke-Petit and her two daughters, 11-year-old Michaela and 17-year-old Hayley.

Testimony resumes Monday. Defense lawyer Walter Bansley III says a forensic psychiatrist will be testifying about Komisarjevsky's mental problems.