An Oakland man convicted of four murders and more than 20 other felonies said Thursday that he thinks his mother and grandmother are partially responsible for his crime spree.

Testifying in the penalty phase of his trial, Demarcus Ralls, 21, said he had a miserable childhood moving from the homes of abusive family members to foster homes and for many years didn't even know the identity of his father.

Ralls said his mother is a drug addict who gave birth to him while serving a jail sentence and his grandmother, who helped raise him, frequently beat him with "whatever she could get her hands on," including a frying pan and broom sticks.

Under cross-examination by prosecutor Darryl Stallworth, Ralls, who was dressed in a yellow sweater and a brown shirt, said no one ever encouraged him to be a good person.

Two weeks ago, at the end of the guilt phase of his trial, jurors convicted Ralls of three counts of first-degree murder, one count of second-degree murder, two counts of attempted murder, 17 counts of robbery, one count of kidnapping and one count of shooting into an inhabited dwelling.

Ralls was one of a group of six people who called themselves the "Nut Cases" because authorities said they engaged in a crime spree that terrorized Oakland over a six-week period in late 2002 and early 2003 mainly for thrills. Some members of the group sported tattoos of the Planters "Mr. Peanut" logo.

Ralls is the first of the "Nut Case" defendants to be prosecuted and the other five are expected to be tried later this year and next year.

At the conclusion of the penalty phase, following closing arguments next week, jurors will choose between recommending either the death penalty or life in prison without parole.

In her opening statement in the penalty phase last week, Ralls' lawyer, Deborah Levy, told jurors that Ralls suffered through "an abhorrent upbringing" and he "spent his life trying to find someplace to belong."

Levy said Ralls began committing crimes at the behest of his older half-brother, Gregory Colbert, whom she said ordered him to murder a man who was having an affair with Colbert's wife while Colbert was in prison.

Ralls was barely responsive when Stallworth asked him if he embarked on his crime spree on his own or did it just to go along with the "Nut Case" group.

"I don't know," he said.

When Stallworth asked if Ralls had any mercy for 31-year-old Sunny Thach, who was robbed and gunned down the night of Jan. 6, 2003, after he and his wife returned to their apartment at 1914 Sixth Ave. after doing their laundry, Ralls responded, "What do you mean?"

Ralls denied Stallworth's allegation that he shot at Thach's wife, Sylvia Tang, who survived the incident, because he didn't want her to be a witness who could incriminate him for Thach's death.

Ralls admitted that he shot at Tang, but said he doesn't know why.

When the prosecutor asked if Ralls was ready to accept responsibility for killing Thach, Ralls quietly answered, "If I did it, yeah." However, he said he doesn't remember shooting Thach.

In his closing argument in the guilt phase of the trial last month, Ted Johnson, another attorney for Ralls, suggested that another member of the "Nut Case" group might have killed Thach.

When Stallworth asked Ralls today if he cared about the people he killed, Ralls said, "At first I didn't, but now I do."

Ralls said he didn't care about his victims until his trial, "When I was sitting at the (defense) table and hearing the people (witnesses) and the evidence."

Ralls said he has written letters to the family members of his victims "asking if they could forgive me for the things I've done" but he said he hasn't mailed them.

Asked by Stallworth why he didn't stop committing crimes, Ralls said, "I don't know. There's a lot of stuff I don't understand."

Testimony in Ralls penalty phase will continue Monday afternoon. Closing arguments are expected to be presented Tuesday or Wednesday.