Whether the Department of Justice can claim the discretionary function exemption (DFE) under 28 U.S.C. § 2680(a) when demonstrating total negligence in failing to investigate an alleged attempted murder

Can the Department of Justice, or any government agency, legitimately 1. claim 28 U.S.C. § 2680(a) discretionary function exemption (DFE) after being indisputely totally negligent as in the present case? In Keller v. United States, 771 F.3d 1021 (7th Circuit 2014), "The discretionary function exception is an affirmative defense to liability under the FTCA that the government must plead and prove." If the DOJ is claiming DFE, and admitting such negligence, how is the required proof possible? Is it enough just to claim DFE for defense in court? DOJ, and the lower courts, cite Baer (Baerv. United States. 722 F.3d 168, (3d Cir. 2013)), in which the 3rd Circuit accepted the government's DFE claim and the government defense won the case. Unlike the present case, where there is total negligence to perform a duty by the government, in Baer the government conducted a multi year investigation and did interviews. In the present case, the DOJ refused to even speak to Trengove, the petitioner, after they received what is arguably proof evidence of an attempted murder. And, multiple complaints. Unfortunately, those involved in the allegation were eventually successful by denying necessary life support resulting in the death of his mother, of whom he was legal caregiver. In the present case, defense cites no similar cases where there was anything like total negligence and DFE was accepted as a defense. 2. Can an Appellate Court maintain a ruling which clearly runs counter to that of other Appellate Courts and greatly weakens FTCA, a legal statutue? For example, in Coulthurst v. United States. 214 F.3d 106, 111 (2d Cir. 2000), the 2nd Circuit ruled against the government's use of the discretionary function exemption (DFE), because laziness or inattentiveness cannot be substituted for discretion or a judgement decision. Likewise, in the present case, the Department of Justice's total negligence should have barred application of DFE. The 2nd Circuit Court also warned in Coulthurst that indiscriminate use of 28 U.S.C. § 2680(a) discretionary function exemption by the government would weaken the FTCA (28 U.S.C. § 1346(b)(1)), which is what the rulings of lower courts in the present case seem to have done. Similarly, in Keller v. United States. 771 F.3d 1021 (7th Circuit 2014), an appellate court decided differently than the 3rd Circuit in this case.