Lauro Jose Aguilar, federal prisoner # 04200-051, appeals the dismissal of the *334 28 U.S.C. § 2241 habeas petition that he filed on behalf of his adopted son Bardo Aguilar-Castro (“Bardo”) seeking derivative citizenship or legal permanent resident status for Bardo. The district court held that it lacked jurisdiction to consider the petition because Aguilar had failed to show that Bardo could not prosecute the action on his own behalf, and dismissed the petition without prejudice.

Because Aguilar is proceeding under § 2241, he need not obtain a COA to pursue his appeal. 1 To bring the instant petition pursuant to § 2242 as Bardo’s “next friend,” Aguilar was required to provide the district court with “an adequate explanation — such as inaccessibility, mental incompetence, or other disability — why the real party in interest cannot appear on his own behalf to prosecute the action.” 2 As the “next friend” it was Aguilar’s burden to “clearly to establish the propriety of his status and thereby justify the jurisdiction of the court.” 3 The district court concluded Aguilar had failed to meet that burden. “In an appeal from the denial of habeas relief, this court reviews a district court’s findings of fact for clear error and issues of law de novo.” 4

Aguilar alleged below that Bardo could not prosecute the action on his own behalf due to mental incapacitation caused by his marital difficulties. On appeal, he argues the district court erred by rejecting this claim as speculative merely because he did not submit a medical professional’s opinion to support this claim. This argument ignores that Aguilar bore the burden of proving Bardo’s incapacitation, however, and therefore does not justify reversal of the district court’s judgment. 5

Aguilar also argues that the district court erred because it presumed Bardo had access to a law library and therefore could have prosecuted the action himself. In support of that claim, he submits an affidavit from Bardo. This also does not aid the appeal. First, the affidavit does not claim Bardo was mentally incapacitated, as claimed by Aguilar before the district court. Second, this court does not consider evidence offered for the first time on appeal. 6

In light of the lack of evidence to support Aguilar’s “next friend” status under § 2242, the district court did not err by dismissing the petition for lack of jurisdiction. 7

AFFIRMED.