I wonder if your source might not be confused with the following soldier of the 1st La. Hvy. Artillery (note the April 3, 1865 capture date):

Metcalf, Enoch B., Pvt. Sergt. Cos. B and I, 1st La. Hvy Arty. (Regulars). En. Feb. 28, 1861, New Orleans, La. Nominated Corpl., June 19, 1861. Apptd. Sergt., Sept. 26, 1861. Captured Fort Jackson, La., April 24, 1862. Sent to New Orleans, La. Exchanged Feb. 23, 1863. Jailed April 1863. Captured and paroled at Vicksburg, Miss., July 4, 1863. Parole Camp, Marion. March and April, 1864, Absent with leave on detached duty in Ord. Dept., Demopolis, Ala. May, 1864, to April, 1865, Absent, discharged from field service, certificate of disability, on detached service at Demopolis or Tuscaloosa, Ala. Federal Rolls of Prisoners of War, Captured Tuscaloosa, Ala., April 3, 1865. Rolls of Prisoners of War, C. S. A., Paroled at Tuscaloosa, Ala., April 4, 1865.