The Tenth Circuit has affirmed the denial of a successive 28 U.S.C. § 2255 motion, holding that a conviction under 21 U.S.C. § 848(e)(1)(B), for intentionally killing a state law enforcement officer in furtherance of a drug crime, categorically qualifies as a "crime of violence" under the elements clause of 18 U.S.C. § 924(c)(3). The court reasoned that the statute requires an intentional mental state, higher than recklessness, because "intentionally" appears in the text and the surrounding verbs, "counsel," "command," "induce," and "procure," connote intent. This is a federal criminal case rather than an immigration case, but it applies the categorical approach used in removability analysis.
The full text of United States v. Barrett can be found here: https://www.ca10.uscourts.gov/sites/ca10/files/opinions/010111533885.pdf