P solicited Art Corona and Paul David Brown to help him rob Michael Kumar, a local drug dealer. On the way, they stopped at Lisa Tapar's house, where P put his buck knife through her front door and scratched a swastika into her car after she refused to talk to him. The three men, who were all armed with buck knives, found no one at Kumar's house, broke in and began ransacking the home. Thomas Johnson and Robert Beckett arrived and shouted that they were calling the police. P and his accomplices tried to escape through the rear door, but Johnson blocked their path. P backed Johnson onto the patio, demanding drugs and money and repeatedly striking him in the chest. Johnson dropped his wallet on the ground and stopped resisting. Beckett then came around the corner, and P attacked him, too, stabbing him repeatedly in the chest. P forced Beckett to the ground, took both men's wallets, and began kicking Beckett in the head. Brown stabbed Johnson in the chest, “‘bury[ing] his knife to the hilt.’” Johnson and Beckett died of their wounds. The three split the proceeds of the robbery: $23 and one quarter-ounce of marijuana. The California trial court appointed Harry Brainard and Wilbur Dettmar to defend P on charges of first-degree murder, robbery, and burglary. Before their appointment, P had rejected other attorneys and insisted on representing himself. During that time, the State had mailed P a letter in jail informing him that the prosecution planned to offer aggravating evidence during the penalty phase of trial to support a sentence of death. Brainard and Dettmar moved to exclude any aggravating evidence on the ground that the prosecution had failed to provide notice of the evidence to be introduced, as required by Cal. Penal Code. The jury unanimously voted for death on each of the two murder counts. On mandatory appeal, the California Supreme Court affirmed the judgment. In August 1993, P filed his first state habeas petition. P alleged ineffective assistance of counsel at the penalty phase of his trial. He alleged that Brainard and Dettmar had failed to adequately investigate and present mitigating evidence, including evidence of mental disorders. The California Supreme Court unanimously and summarily denied P's penalty-phase ineffective-assistance claim “on the substantive ground that it is without merit.” P filed a federal habeas petition in April 1997. He reiterated his previous allegations about penalty-phase ineffective assistance and also added new allegations that his trial counsel had failed to furnish Dr. Stalberg with adequate background materials. Dr. Stalberg provided a declaration stating that in 1984, P's trial counsel had provided him with only some police reports and a 1978 probation report. Dr. Stalberg explained that, had he known about the material that had since been gathered by P's habeas counsel, he would have conducted “further inquiry” before concluding that P suffered only from a personality disorder. P filed a second state habeas petition, this time including Dr. Stalberg's declaration and requesting judicial notice of the documents previously submitted in support of his first state habeas petition. The California Supreme Court again unanimously and summarily denied the petition “on the substantive ground that it is without merit.” The District Court granted habeas relief. The Court of Appeals affirmed the District Court's grant of habeas relief. The Supreme Court granted certiorari.