Luke 8:41-42 describes Jairus's daughter as dying, at the point of death, when Jesus is summoned, while Matthew 9:18 has Jairus say his daughter 'has just died' already at the outset -- the Gospels disagree on whether the girl was alive or dead when Jesus was first approached.

This is best explained by standard, well-documented ancient biographical compression, expected within the conventions of Greco-Roman bios, the genre to which the Gospels belong (Richard Burridge's work on Gospel genre establishes this). Mark (5:22-24, 35-43) and Luke (8:41-42, 49-56) preserve the fuller two-stage version: Jairus initially reports his daughter dying or at the point of death, Jesus proceeds toward the house, and only partway there does a messenger arrive reporting she has since died. Matthew's account (9:18-26) is demonstrably the most abbreviated of the three tellings of this whole pericope -- it also omits other details Mark and Luke retain, such as Jairus's name and the woman-with-the-hemorrhage backstory. Matthew simply skips the intervening messenger scene and narrates Jairus's initial report directly in terms of the end-state that becomes true by the time Jesus arrives, a recognized compression technique of ancient historiography and biography (compare Plutarch's frequent telescoping of events), not a factual clash about what actually happened.

Matthew's consistent pattern of abbreviating Markan material throughout this and other shared pericopae, a broader and well-documented feature of Matthew's redaction (consistent with Markan priority), provides independent structural confirmation that this is stylistic compression rather than an ad hoc harmonizing invention -- it fits a pattern found throughout the Gospel.