The Board of Immigration Appeals has determined that “[w]here a presumption of a future threat to life or freedom applies, an Immigration Judge cannot rely on generalized crime and widespread violence unrelated to the original claim to find the presumption has not been rebutted, particularly where other evidence suggests a fundamental change in circumstances such that a respondent will no longer be harmed on account of a protected ground.”
The full text of Matter of R-B-E- can be found here: https://www.justice.gov/eoir/media/1430191/dl?inline