Otsemobor, 22, joined
Liverpool in the summer of 2002 but has failed to make the breakthrough at Anfield and has been farmed out on loan to Hull,
Bolton and Crewe.
He arrived at Hearts on Monday and will spend the remainder of the week training with the squad at the club's Riccarton complex.
Robertson told the Edinburgh Evening News: "Jon was recommended to us and he is here for a few days so we can have a look at him.
"We also have a trialist keeper here this week and a couple of others over a few age groups."
