A judge ordered a second round of psychiatric evaluation Tuesday for an Upper Merion man charged in the slayings of three family members.

Joseph McAndrew Jr., 23, has been held at Norristown State Hospital since investigators accused him of killing his mother, father and twin brother James with an 18-inch samurai-style sword. Their bodies were found March 5 in a bloody crime scene at their Gulph Mills home.

But within days of his arrest, doctors declared McAndrew unfit to proceed with a preliminary hearing. He said little in jail and refused to sign documents that would have given him a court-appointed attorney or mental health treatment.

Since then, though, McAndrew has shown signs of improvement, prosecutors argued this week. Since a judge ordered him to receive additional treatment, he has started to communicate with hospital staff and has asked for time to socialize with other inmates in the facility's yard, said Assistant District Attorney Kate McGill Magid.

McAndrew's public defender - Denise Marone - maintained, however, that neither development proves her client has the mental capacity to understand the charges.

It remains unclear whether McAndrew was ever officially diagnosed or received treatment for a mental disorder before his alleged attack. Those who would know best - his father Joseph C. McAndrew, 70, and mother Susan McAndrew, 64 - died, detectives have said.

Shortly after the slayings, investigators found a book titled Dealing with Schizophrenia in the McAndrew house. And several of James McAndrew's friends recalled him talking often about his brother's condition.

Statements Joseph McAndrew made shortly after his arrest - including a cryptic admission to officers that an "extermination" had killed "a person named brother," "a person named father," and "and a person named mother" - suggest some form of mental disturbance but also an awareness of what had gone on around him, prosecutors said.

In an order Tuesday, Judge William R. Carpenter agreed to a second round of testing by a prosecution psychiatrist. Should McAndrew be found competent to proceed, his case would be set for preliminary hearing shortly thereafter.

He remains held without bond and charged with counts of first- and third-degree murder as well as one count of possessing an instrument of crime.

Contact staff writer Jeremy Roebuck at 267-564-5218, jroebuck@phillynews.com, or @inqmontco on Twitter. Read his blog, "MontCo Memo," at www.philly.com/montcomemo