The gang stopped the train, holding it up at gunpoint, and made off with about $20,000. During the robbery, the conductor had sneaked away, making his way to Nutt, where he telegraphed for help. Soon, a posse from Lake Valley, 18 miles to the north was on its way. However, by the time the posse arrived, the gang was well hidden in their safe house, and Black Jack soon slipped into Arizona. The $20,000 was never found.

On December 12, 1895, Tom and several other men shot and killed John N. "Jap" Powers, a neighbor in Tom Green County, Texas. Tom later admitted he took part in the murder, but claimed he was paid to do it.  After this episode, Tom and Sam high-tailed it out of Texas back to New Mexico

While in New Mexico, the Ketchum Gang were well known at many of the dances, social functions and saloons in northeast New Mexico. These well-mannered young men, riding good horses, flashing plenty of money, and claiming to be cowboys, would arrive at the local functions where the women were enraptured by their manners. They were known to have frequented several establishments in Elizabethtown as well as Cimarron, specifically Lambert's Inn (now the St. James Hotel.) Not until later, when they were captured, did townspeople learn these young men were actually members of Black Jack Ketchum's outlaw gang.

After leaving Texas in late 1895, the brothers worked at the Bell Ranch until sometime in early June 1896, when they quit, stealing supplies from the ranch before they left. On June 10th, they showed up at the small settlement of Liberty, New Mexico, north of present-day Tucumcari.

During the night, they robbed a local store and post office, which was operated by Levi and Morris Herstein.

The Ketchum brothers rode hard to the Pecos River after the robbery, with Levi Herstein and several other men chasing after them. A gun battle ensued at the Pecos River, leaving most of the posse dead. The brothers then headed west to Arizona, were they sometimes rode with Butch Cassidy's Hole-in-the-Wall Gang.

Apparently the Ketchum Gang felt confident in robbing trains in this specific area of New Mexico, between Folsom and Des Moines. The area was the point where the old wagon road crossed the Colorado and Southern Rail tracks near Twin Mountain.

Their habit was to stop the train and uncouple the mail and express cars, which were then taken about a mile and a half down the track and looted. On September 3, 1897 Black Jack and his gang were back at it, robbing another train, making off with about $20,000 in gold and $40,000 in silver. They escaped after the robbery, hiding in a cave south of Folsom, New Mexico where they remained until the next day.

On July 11, 1899, the gang struck again, this time without the help of Black Jack. After camping at the head of Dry Canyon in northeast New Mexico, Sam Ketchum, Bill Carver, Elza Lay, and an outlaw named McGinnis made off with some $50,000 from the train in Folsom, New Mexico. They were soon pursued by a posse to a hideout near Cimarron, New Mexico. The outlaws were better armed with high-powered rifles and smokeless powder, while the posse had conventional black powder guns, the smoke of which, gave away their positions.

Sam Ketchum and McGinnis were both wounded in the gun battle and captured. The posse faired even worse, with two of its members, including Sheriff Edward Farr, killed and another posse man injured. Both Sam and McGinnis were taken into custody, where Sam developed gangrene from his wound. On July 24, 1899 he died in the Santa Fe penitentiary and was buried in the Odd Fellows Cemetery.

McGinnis later recovered to serve time in the Santa Fe penitentiary. On August 16th, Elza Lay was arrested and was later tried and convicted for the murder of Ed Farr and sentenced to life in prison. Carver escaped to ride with the Wild Bunch.