ELK POINT, S.D. -

The Union County Sheriff’s Office has released new information in the search of a man who went missing while swimming in the Missouri River.

Originally witness accounts said that Tom Patterson, 23, of Frostburg Md. tried to swim across the Missouri River near Elk Point with four of his friends. Limoges says that authorities were told that the four friends made it, but Patterson did not.

Union County Sheriff Dan Limoges says that new witness accounts says that five people swam across the river to the Nebraska line, but Patterson stayed behind. After 30 minutes one person swam back to the South Dakota side to be with Patterson.

According to Limoges, the witness said that the four on the Nebraska side did not know how to get back to the South Dakota side. The group decided to meet in the middle of the river, to help each other across back to the South Dakota side.

Limoges says Patterson took a dog leash and tied it around himself to use it as a tether to help the other four swim across. Patterson did not make it to the middle of the river, as the current pulled him away and eventually underwater.

The search for Patterson continues by boat and plane through efforts of both South Dakota and Nebraska authorities.