The earliest documentation of him in the U.S. is an 1848 affidavit in which Waltz declared himself to be "about 38 years old". A man called Jacob Waltz was born in September 1810 in Württemberg. It is suggested that this Waltz could be the same Waltz who later came to be regarded as the legendary Dutchman, and that he Americanized the spelling of his name. Note that tombstone pictured shows birth year as 1808.

Waltz relocated to Arizona in the 1860s, and stayed in the territory for most of the rest of his life. He pursued mining and prospecting,  periodically appeared with large amounts of gold, The Sterling Legend by Estee Conatser reports that a Jacob Walzer sold $250,000 in gold to the U.S. Mint during the 1880s and had $1500 when he died in 1891. In 1870, Waltz had a homestead of about 160 acres (0.65 km2) near Phoenix where he operated a farm.

There was a catastrophic flood in Phoenix in 1891, and Waltz's farm was one of many that was devastated. Afterwards, Waltz fell ill (he was rumored to have contracted pneumonia during the flooding). He died on October 25, 1891, after having been nursed by an acquaintance named Julia Thomas (she was usually described as a quadroon). Waltz was buried in Phoenix at what is now called the Pioneer and Military Memorial Park.

 Waltz related to Thomas the location of an alleged gold mine. As early as September 1, 1892, The Arizona Enterprise was reporting on the efforts of Thomas and several others to locate the lost mine whose location was told to her by Waltz. 

Jacob Waltz said:

1. If you climb some distance above my mine you can see to the south a sharp peak (Weavers Needle).

2. Waltz said that from up above my mine you cannot climb straight down, that you have to go a little way along the top of the mountain, then climb down and then backtrack toward the mine and climb back up to get back to the mine.

3. He said the mine lies in a north trending canyon that is shaded most of the day.

4. From the mine you can see four peaks, but it looks like one peak.

5. Waltz said that when he traveled there, he camped the night below the fort in a stand of Cottonwoods.

6. The next day he crossed at the gravel bar and then he traveled to first water and then on to second water.

7. Waltz said … Then I went to the spring and followed the old Indian Trail up to the mine.

8. He continued by saying that just below the mine is a tunnel the Mexicans dug, trying to come at the mine from below. Waltz said he built a rock wall in the opening to hide it.

9. Waltz said he camped up above where the Mexicans camped on the Horse’s Saddle. He also said he hid his tools there when he left.

10. Waltz said his mine-opening faces toward the northwest and late in the day the sun shines in the opening into the mine and on gold.

11. Waltz said the Mexicans dug another tunnel from down below the mine trying to come in farther down into the vein because the pit mine was getting too hard to mine. He said that he too tried to dig a mine just above them, but as the Mexicans had said, the rock in this section was too hard, so he gave up as well. He also said his shaft and the Mexican’s shaft were very close together, but when you stood at either shaft you cannot see the other shaft.

12. He said you can be twenty feet from my mine and you will not have any idea where it is.

13. He said before his partner was killed, they stayed in a cave above and across from the mine either 200 feet or 200 yards.

14. Waltz said there is trick to his trail and no miner will ever find his mine.

15. Waltz said that at the head of a north-trending canyon you will find the ruins of an ancient Spanish house that sits hidden on a ledge, and that the climb up to it is so steep that you will not see it until you scale up onto the ledge that it sits on, as its stone walls lay before you. He said if you find this house at the head of a steep north-trending canyon you are not far from the mine.

16. He said he had to slide in through a small opening, and that he chiseled it a bit so he could get in and out of the mine.

Here's where things get mixed up!