Given the following context:

Tired of killing, war veteran Jefferson Waring rides west, but in Missouri he sees "squatters" mowed down by men working for rich, ruthless Artemus Taylor.
He spends the night at Independence newspaperman Peter Sharpe's place, but is jailed when daughter Cathy Sharpe finds this total stranger in her room. The local marshal, John Harding, is just one of many men on Taylor's payroll.
Peter's business is threatened by banker Stone unless he takes Taylor's side against "squatters" settling in the region. The blind and wheelchair-bound Taylor and ambitious daughter Norah are secretly aware that railroad surveyors are considering laying tracks nearby, so they want all the land for themselves.
Jeff decides to leave. Norah and henchman Ding Bell intercept him; Norah shoots at him but misses. They take him to see Artemus, who tells a vocally reluctant Bell to take Jeff off to a remote canyon and murder him. Under Norah's instructions, Artemus's chief thug Sam Tobin goes after them to murder both; he wounds Jeff and kills Bell, but not before Bell hits him with a fatal shot. A doctor treats Jeff's wounds but Marshall Harding turns up and charges Jeff with the two killings.
When the situation escalates and two of Taylor's thugs gun down Peter Sharpe, Jeff breaks out of jail and organizes a group of settlers to resist Taylor's planned big attack. The settlers slaughter Taylor's thugs; Taylor dies of a heart attack; Norah, having shot and she thinks killed banker Justin Stone in order to get some getaway money, is killed by him as she leaves. Jeff stays in town to run the paper with Cathy.

answer the following question:

What are the first names of the people that Tobin goes after? 

Ding