Martín de Estepa was listed on the 1540 muster as a member of Vázquez de Coronado's company. Fellow expeditionary Alonso Sánchez reported that Estepa set dogs on Indians, most likely on the orders of López de Cárdenas. This name is uncommon so it is highly likely that references to Martín de Estepa refer to the expeditionary. It appears that upon the return of the Expedition he remained in Culiacán.
1540, Feb: Muster in Flint & Flint, Documents, Document 12 [horse, native arms, in the company of Vázquez de Coronado]
AGI, Justicia, 267, N.3, “Proceso de Francisco Vázquez” [witness Alonso Sánchez: Martín de Estepa, man-at-arms, set dogs on Indians] = AGI, Justicia, 1021, pieza 4]
?AGGEC, Juan de la Torre, Registro 2 [p.42-44, s/f: will of Lazaro del Valle, vecino of Colima; he owes Martin de Estepa, vecino of Culiacán 12 or 15 pesos];
?Hillerkuss, Diccionario Biográfico, vol.2 [accused of crimes against Indians; 1548, vecino of Culiacán; owes money to Lazaro del Valle, vecino, delivered his will 2:93];
?AGI, Contaduría, 664, 1559 [monies spent on explorations: Carta de pago de Angel de Villafaña e de los harineros que recibieron el biscocho que entrego don Felipe en La Puebla 1559: Martin de Estepa received 40 quintales of bizcocho blanco, 4 April, and signed for it; and, harriero, 342 arrobas of çeçina [salted meat] to San Juan de Ulua, 17 April]
?AGI, Contratación, 473, N.1, R.1, exp. 9 [May 1567; in April 1566, a Miguel de Tórres is a witness twice in Culiacán, so is a Pedro de Torres, both vecinos of Culiacán; another witness (to a declaration by the alcaldes and regidores) is Pedro de Nájera, vecino of Culiacán, he also signs as a witness to an accounting of the estate of Juan de Aragón; during the almoneda in Culiacán Martín de Estepa buys 3 fisnos? and more than 10 achuelos and 6 pairs of zapatos traidos and una frezada and a alnylla de grana and some boots and un obillo de hilo and un talabarte bellaco and a gineta bit and espuelas de gorrión and 2 petacas and 2 pairs of scissors, for all of which he presented two IOUs totalling 12.5 pesos; a Pedro Martín buys 8 varas of anje? and 17 obillos de ballesta and 1 frezada and 7 panes de carbón and a capa, in June 1565 Martín serves as a witness en las minas de las vírgenes, provincía de Culiacán; in another almoneda in July 1565 in Culiacán, don Pedro de Tovar buys 14 libras de canela and an espada; an Hernán González, along with two other men, buys 9.5 varas de tocasa? de estas mynas, he also signs for a witness (no signaturenature); Pedro de Nájera buys cierto azafrán for 3 pesos and 2 tomines]