SUMMARY ORDER

Petitioner Chandrika Jayalalani Perera, a native and citizen of Sri Lanka, seeks review of a December 18, 2003 order of the Board of Immigration Appeals, affirming the March 11, 2003 decision of Immigration Judge (“IJ”) Robert D. Weisel, denying her application for asylum, withholding of removal, and relief under the Convention Against Torture. In re Chandrika Jayalalani Perera, No. A95 864 132 (B.I.A. Dec. 18, 2003), aff'g No. A95 864 132 (Immig. Ct. N.Y. City Mar. 11, 2003). We assume the parties’ familiarity with the underlying facts, the procedural history, and the issues presented for review.

*394Where, as here, the BIA issues an opinion that fully adopts the IJ’s decision, this Court reviews the IJ’s decision. See, e.g., Chun Gao v. Gonzales, 424 F.3d 122, 124 (2d Cir. 2005); Secaida-Rosales v. INS, 331 F.3d 297, 305 (2d Cir. 2003). This Court reviews the agency’s factual findings, including adverse credibility determinations, under the substantial evidence standard, treating them as “conclusive unless any reasonable adjudicator would be compelled to conclude to the contrary.” 8 U.S.C. § 1252(b)(4)(B); see, e.g., Zhou Yun Zhang v. INS, 386 F.3d 66, 73 & n. 7 (2d Cir. 2004).

In addition to providing testimony and supporting documentary evidence that is otherwise unimpeached, Perera submitted a December 10, 2001 letter purporting to have been written by her doctor (Fernando) and corroborating the injuries she testified to have suffered in the course of rape. [JA 159-60]. The IJ found that this letter is inauthentic. That finding is supported by substantial evidence: the doctor was dead on the date of the letter.

The IJ relied on the inauthenticity to discredit the rest of Perera’s evidence. However, the IJ failed to consider whether the letter is “documentary evidence that the alien does not know, and has no reason to know, is inauthentic.” Siewe v. Gonzales, 480 F.3d 160, 171 (2d Cir. 2007).2 That is a question to which the answer is not obvious. Accordingly, we remand to the agency for a determination of whether Perera knew or or should have known of the fraudulent nature of Dr. Fernando’s letter.

We have considered Perera’s remaining arguments and deem them to be without merit.

For the foregoing reasons, the petition for review is GRANTED, the BIA’s order is VACATED, and the case is REMANDED to the BIA for further proceedings consistent with this order.