Alexander joined the mission to use the island's Velociraptor pack to track down the escaped Indominus rex. He was later killed by raptor Delta when the pack was convinced by the Indominus to turn against the humans.
On Isla Nublar
Alexander was part of the private military team deployed on Isla Nublar in 2015 to handle the ongoing situation on the island. He was sent into the restricted area along with the other troops to find the Indominus, using Owen Grady's raptors to track the creature down.
When the Velociraptors located the Indominus, the hybrid used her raptor DNA to communicate with the raptors and eventually convinced them to side with her, becoming their new leader. The pack then fled into the jungle with the Indominus when the troops fired at the creature. Alexander and the others cautiously followed the dinosaurs into the forest.
Shortly afterward, the team was ambushed by the raptor pack, and within moments most of the team was decimated by the pack. Alexander became disoriented in the ensuing chaos; unfortunately for him, Delta used this opportunity to ambush him from behind. By the time Alexander turned around and noticed his attacker, it was too late — Delta leaped at Alexander and took him to the ground, tearing him apart and brutally killing him.
Behind the scenes
His name might be a reference to the visual effects supervisor of Jurassic World Tim Alexander.