Speaker
Matthew, Mark, and John were actually the disciples of Jesus, and Mark was a companion of Peter. Luke was a traveling companion of Paul. We see this based on Colossians 4.14 and 2 Timothy 4.11, and he was basing his account off of eyewitness accounts. Then we have Romans, 1 and 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1 and 2 Thessalonians, 1 and 2 Timothy, and Titus.