*245OPINION
By the Court,
Young, J.:In 1985, appellants Dale Flanagan and Randy Moore were convicted of murdering Flanagan’s grandparents. Both Flanagan and Moore were sentenced to death and separately appealed to this court. We affirmed their convictions but reversed the sentences of death based on cumulative prosecutorial misconduct. See Flanagan v. State, 104 Nev. 105, 754 P.2d 836 (1988) and Moore v. State, 104 Nev. 113, 754 P.2d 841 (1988). Following a joint retrial of the penalty phase in July 1989, Flanagan and Moore were again sentenced to die. Although separately briefed and argued on appeal, we have consolidated our decisions in these cases due to the common issues presented. NRAP 3(b).
This case involves the shooting deaths of Flanagan’s grandparents, Carl and Colleen Gordon. The Gordons were found dead on November 6, 1984, Carl having been shot seven times in the back and chest and Colleen having been shot three times in the head. On direct appeal, we found overwhelming evidence that Flanagan, Moore and four other co-defendants killed the Gordons so that Flanagan could obtain insurance proceeds and an inheritance under his grandparents’ will. Flanagan, 104 Nev. at 107, 754 P.2d at 837.
At the second penalty hearing, the State called eight witnesses. In addition, Flanagan gave a brief unsworn statement to the jury in which he acknowledged that he had been involved in occult activities. Moore also gave an unsworn statement to the jury in which he admitted practicing white witchcraft.
The jury imposed sentences of death. On the special verdict form, the jury checked two mitigating circumstances: (1) the defendants’ lack of significant history of prior criminal activity, and (2) “any other mitigating circumstance.” In addition, the jury found four aggravating circumstances: that the murders were committed: (1) by defendants who knowingly created a great risk of death to more than one person; (2) while the defendants were engaged in the commission or attempted commission of a burglary; (3) while the defendants were engaged in the commission or attempted commission of a robbery; and (4) for the purpose of receiving money or any other thing of monetary value. Following sentencing, these appeals were filed.1
*246 Flanagan and Moore’s Common Contentions
Appellants Flanagan and Moore first contend that the district court erred in admitting testimony regarding their involvement in satanic worship in 1982 when they were 17 years old. Appellants argue that the evidence concerning this activity was dubious and irrelevant. They further argue that, even if the evidence is considered relevant, the district court should have excluded it because any probative value was substantially outweighed by the danger of unfair prejudice, of confusion of the issues and of misleading the jury. See NRS 48.035(1). Appellants also assert that the prosecutor’s argument regarding satanic worship inflamed the jury and diverted it from making its sentencing decision based on relevant evidence. Appellants contend that the admission of this evidence rendered the trial fundamentally unfair and the verdict arbitrary and capricious.
One of the State’s witnesses, Thomas Akers, testified that he had seen Flanagan play with tarot cards and that Flanagan had told him he was “into” devil worship. Akers also said that Flanagan told him he had the power “to push them [the Gordons] up or down, whatever he wanted.” He further testified that he, Akers, had drawn a picture of a wizard and named it “Dale.” A second State’s witness, Wayne Wittig, testified that at age 16 he had been part of a seven-member “coven” led by Flanagan and Moore. Wittig stated that Flanagan represented black magic and Moore represented white magic, which meant that Flanagan was more the physical part of the coven, while Moore was more the mind-over-matter part. He also testified about an initiation ritual involving use of a knife to draw blood and running the blade through a candle flame “to create a centralness.”
Appellants contend that the evidence of their belonging to a coven in 1982 was irrelevant because there was no evidence or suggestion that this previous activity was a causal factor or otherwise related to the crimes committed in late 1984. In addition, appellants contend that the evidence was irrelevant because there was no evidence that the coven had a sinister purpose or was committed to evil. Moore also argues that the evidence was dubious and irrelevant because there was no evidence other than that he belonged to the coven. Relying on Woodson v. North Carolina, 428 U.S. 280 (1976), appellants maintain that the *247evidence was irrelevant because it was not part of their individual characters and the particular circumstances of the crime.
We conclude that this evidence was both relevant and properly admitted by the court. Under NRS 175.552, during a penalty hearing “evidence may be presented concerning aggravating and mitigating circumstances relative to the offense, defendant or victim and on any other matter which the court deems relevant to sentence, whether or not the evidence is ordinarily admissible.” (Emphasis added.) We have held that NRS 175.552 is not limited to the nine aggravating circumstances outlined in NRS 200.033. See Allen v. State, 99 Nev. 485, 488, 665 P.2d 238, 240 (1983); see also, Biondi v. State, 101 Nev. 252, 257, 699 P.2d 1062, 1065 (1985). Accordingly, the district court did not err in admitting the testimony about satanic worship.
Appellants also assert that the district court erred by allowing the State to use a constitutionally protected activity to seek the death penalty. Appellants rely on Zant v. Stephens, 462 U.S. 862 (1983), in which the United States Supreme Court reiterated its earlier decisions prohibiting aggravating circumstances based on constitutionally impermissible factors such as religion. Id. at 885. See, e.g., Herndon v. Lowry, 301 U.S. 242 (1937). Here, however, the jury found four aggravating circumstances, none of which rested upon or involved constitutionally protected activities. Even assuming that the testimony regarding satanic worship involved constitutionally protected activity, Zant does not concern such character evidence.
Flanagan and Moore further contend that the district court’s allowance of testimony regarding the sentences of the other four co-defendants violated their Eighth Amendment rights to have the jury consider their individual characters and records and the circumstances of their particular crimes. See Woodson v. North Carolina, 428 U.S. 280, 304 (1976). Appellants cite authority from several other jurisdictions in support of their argument that the prosecution should not have been allowed to introduce and argue this evidence. See, e.g., People v. Belmontes, 755 P.2d 310 (Cal. 1988).
At trial, the district court allowed testimony by one of the prosecutors from the original trial and penalty hearing. The prosecutor testified that co-defendant Johnny Ray Luckett had received four consecutive sentences of life without the possibility of parole, and that co-defendant Roy McDowell had received four consecutive sentences of life with the possibility of parole.
We conclude that the district court did not err in allowing the *248testimony about the sentences of the other co-defendants. The evidence was admissible under NRS 175.552 as “any other matter which the court deems relevant . . . .” Furthermore, the jury was instructed that it was not bound by the previous sentences. We believe that it was proper and helpful for the jury to consider the punishments imposed on the co-defendants. See State v. McKinney, 687 P.2d 570 (Idaho 1984).
Appellants next contend that Jury Instruction 15, which told the jury that “[a] verdict may never be influenced by sympathy, prejudice or public opinion” violated their Eighth Amendment rights because it undermined the jury’s constitutionally mandated consideration of mitigating evidence.
We have upheld virtually identical instructions in several other cases. See Howard v. State, 102 Nev. 572, 729 P.2d 1341 (1986); Nevius v. State, 101 Nev. 238, 699 P.2d 1053 (1985); Biondi v. State, 101 Nev. 252, 699 P.2d 1062 (1985); Milligan v. State, 101 Nev. 627, 708 P.2d 289 (1985). In upholding a similar instruction in Nevius, we determined that the jury was fully advised “regarding the range of mitigating circumstances” it could consider. Nevius, 101 Nev. at 250, 699 P.2d at 1061.
As in Nevius, we hold that, because the penalty jury was properly instructed to consider any mitigating circumstances, the district court did not err in instructing the jury that it should not be influenced by sympathy, prejudice or public opinion. See Nevius, 101 Nev. at 251, 699 P.2d at 1061. Although appellants evidently urge this court to depart from our earlier decisions in Howard, Nevius, Biondi, and Milligan, we decline to do so.
Flanagan’s Remaining Contention
Flanagan also contends that Jury Instruction 82 violated his Eighth Amendment rights because it precluded the jury from considering and giving effect to relevant mitigating evidence. Relying on several United States Supreme Court decisions, Flanagan argues that, although he was permitted to introduce mitigating evidence as constitutionally required, the instructions on mitigation, namely Instruction 8, had the effect of telling the jury not to consider relevant mitigating evidence. See, e.g., *249Penry v. Lynaugh, 492 U.S. 302, 109 S.Ct. 2934 (1989). Therefore, Flanagan contends that Instruction 8 resulted in a death sentence which was arbitrary and capricious because it failed to properly guide the jury regarding mitigation.
Flanagan specifically contends that Instruction 8 was constitutionally deficient because the introductory language, “even though the mitigating circumstance is not sufficient to constitute a defense or reduce the degree of the crime,” would cause a reasonable juror to consider his mitigating evidence as irrelevant because it was unrelated to the crime itself. Next, Flanagan specifically contends that Instruction 8 was constitutionally defective because use of the “catch all” language in number 3 of the instruction, “any other mitigating evidence,” failed to provide specific guidelines for considering mitigating evidence of his character and background.
However, our review of Instruction 8 persuades us that a reasonable juror would conclude that mitigation was not restricted to crime-related factors because it was stated that the mitigating circumstances did not have to constitute a defense or reduce the degree of the crime. Furthermore, the jury in fact found two of the three mitigating circumstances to exist. In addition, the instructions as a whole adequately informed the jury of its right and duty to consider mitigating evidence. Finally, it is highly unlikely that a different outcome would have resulted from more specific instructions, given that the evidence of aggravating circumstances was overwhelming and clearly outweighed the mitigating circumstances found by the jury. Thus, we conclude that Instruction 8 did not violate the Eighth Amendment by impermissibly limiting the jury’s consideration of mitigation to evidence related to the crime.
Moore’s Remaining Contentions
Moore also contends that the district court erred in refusing his proposed jury instruction regarding mitigation. Citing Skipper v. South Carolina, 476 U.S. 1 (1986), Moore argues that the refusal resulted in the jury not being advised that it could consider whatever it wanted to be a mitigating circumstance.
We have consistently held, however, that “it is not error to refuse to give an instruction when the law encompassed therein is substantially covered by another instruction given to the jury.” Ford v. State, 99 Nev. 209, 211, 660 P.2d 992, 993 (1983). The other jury instructions, in particular Instructions 6 through 9, adequately informed the jury about the relevant law. These instructions told the jury that it was its duty to determine whether any mitigating or aggravating circumstances existed, and that it *250could only impose a sentence of death if the aggravating circumstances were established beyond a reasonable doubt and if no mitigating circumstances outweighed the aggravating circumstances. The jury was apprised of the circumstances by which the crime could be aggravated or mitigated, including “any other mitigating circumstance.” Therefore, we conclude that Moore’s proposed instruction was properly refused because the information was adequately covered by the jury instructions given.
Additionally, Moore asserts that the district court erred by rejecting his proposed instruction in place of Instruction 6.3 Moore contends that Instruction 6 failed to clarify that the burden rested on the State to prove that aggravating circumstances outweighed mitigating circumstances. Our review of the jury instructions, including Instruction 6, reveals that the instructions as a whole adequately informed the jury of the State’s burden of proof. We conclude that the district court did not err in refusing Moore’s proffered instruction.
Finally, Moore contends that the district court erred by rejecting his motion for severance prior to the second penalty hearing. However, this issue was decided in the first appeal and became the “law of the case.” Hall v. State, 91 Nev. 314, 315, 535 P.2d 797, 798 (1975).
We conclude the sentences were not excessive considering the crimes and the characteristics of the defendants. Having found that appellants’ contentions lack merit, we hereby affirm their death sentences.
Mowbray, C. J., and Steffen, J., concur.At sentencing on July 31, 1989, Flanagan waived his appeal of the death penalty and requested that he be executed on the date set. The district court found that Flanagan’s waiver of his right to appeal was knowing and voluntary. Thereafter, defense counsel filed a designation of the record of the proceedings and, the next day, a notice of waiver of appeal.
Upon receipt of the notice of waiver of appeal, this court entered an order *246staying execution of Flanagan’s death sentence and remanding to the district court for appointment of independent counsel to brief the question of whether Flanagan had validly waived his appeal rights. The district court appointed Lee Elizabeth McMahon who subsequently indicated that Flanagan did not wish to waive his appeal rights and be executed.
Instruction 8 told the jury that:
Murder of the First Degree may be mitigated by any of the following circumstances, even though the mitigating circumstance is not sufficient to constitute a defense or reduce the degree of the crime:
(1) That defendant has no significant history of prior criminal activity.
(2) The youth of the defendant at the time of the crime.
(3) Any other mitigating circumstance.
Instruction 6 stated, in relevant part:
The jury may impose a sentence of death only if it finds an aggravating circumstance has been established beyond a reasonable doubt, and further finds that there are no mitigating circumstances sufficient to outweigh the aggravating circumstance found.
Moore’s proposed instruction stated:
The jury may impose a sentence of death only if it finds at least one aggravating circumstance has been established beyond a reasonable doubt and further finds that the aggravating circumstance (s) outweigh the mitigating circumstance or circumstances found.
(Emphasis added.)