Trying to decipher the correct name of this hacienda and the owner of the sugar factory machinery and scant ruins photographed below has proven to be a difficult task.  One thing is certain though, in the 1860s and 70s they belonged to Hacienda San Isidro of Molinari, Espendez & Cia., as evidenced by a water right to take water from the Jacaboa River granted to Molinari, Espendez & Cia. on March 23, 1866 for irrigation purposes at their Hacienda San Isidro.  The firm Molinari, Espendez & Cia. was a partnership comprised of Italian immigrant from Genoa Francisco Molinari and French immigrant from Bagnères-de-Luchon Juan Alexis Espendez.  Francisco Molinari married Rufina Sanchez of Guayama and also owned Hacienda Las Mercedes in Guayama.  They were the parents of Rufina Molinari Sanchez (1850-1914) the second wife of Ignacio Diaz Joglar, owner of Hacienda Carlota and Hacienda Palés.  Based on information found in La Gaceta de Puerto Rico, Molinari established himself in Patillas in 1841 and in the 1880s, most likely after selling Hacienda San Isidro as stated below, moved his residence to Guayama.

The date when Molinari, Espendez & Cia. acquired Hacienda San Isidro is unknown, but a prior owner is known. La Gaceta de Puerto Rico edition of December 9, 1880 published a notification stating that on June 7, 1833 the partnership Ricci & Curioni mortgaged Hacienda San Isidro in Barrio Jacaboa for 2,371.75 pesos in favor of Mr. Santos Santelli.  The same edition also published a notice stating that on May 31, 1854 Antonia Filippón of Guayama mortgaged for 16,592 pesos macuquinos Hacienda San Isidoro in Barrio Jacaboa in favor of Luis Mariani & Co. and another one stating that the same Antonia Filippón on October 31, 1855 mortgaged Hacienda San Isidoro in Barrio Jacaboa for 1,350 pesos in favor of Joaquín García Orozco.  Other notifications that do not mention the name of the mortgaged property make reference to a Domingo Ricci and Antonio Curioni & Co. who could be the members of the partnership Ricci & Curioni.

Issues of La Gaceta de Puerto Rico and the Boletin Mercantil dated between 1868 and 1874 include notices required regarding the bankruptcy of Molinari, Espendez & Cia. who was declared bankrupt in 1868.  That year a reorganization plan was approved that called for Francisco Molinari as debtor in possession to continue operating Hacienda San Isidro.  The plan called for full payment to creditors without interest in a twelve year period.  The notices required Molinari to publish annual financial reports on the result of operations of Hacienda San Isidro, the only income producing asset of the bankrupt firm.

According to this List of Barrios and Sectors of Patillas, there is a "Sector Merle" in Barrio Jacaboa of Patillas where the ruins and machinery pictured below are located.  The Merle family in Puerto Rico was started in Mayagüez by French immigrant Felipe Merle and his Corsican immigrant wife Isabel Guilfucci.  Part of the family relocated to Patillas and part became coffee farmers in the town of Las Marias where there is also an area called "Sector Merle".  Bernardo Merle Guilfucci (1831-1918) and José Merle Guilfucci (1831-1903) left Mayagüez for Patillas sometime in the 1850s where they established residence in Barrio Jacaboa.  There is no certainty this hacienda was ever owned by either of the Merle brothers while it was a sugar plantation.  Bernardo engaged in businesses activities other than agriculture as verified by the Directorio Comercial e Industrial de la Isla de Puerto Rico published in 1894 and the Colonial Business Directory of the Island of Puerto Rico published in 1898 both of which show Bernardo as a retailer of groceries and provisions.  However, their death certificates identify them as farmers residents of Barrio Jacaboa of Patillas.

There are reports that Hacienda San Isidro was owned by Dr. Antonio José Amadeo Antonmarchi (1844-1904) and destroyed by fire in February 1885 while in his ownership.  As stated above, Francisco Molinari relocated to Guayama in the late 1880s, most likely after selling the hacienda to Dr. Amadeo.  It appears that Dr. Amadeo rebuilt the hacienda after the fire and continued processing sugarcane in it.  As was the case with most of the haciendas in the Maunabo-Patillas area, it was destroyed by hurricane San Ciriaco in 1899 never to process sugarcane again. 

The book Biografía de las Riquezas de Puerto Rico published in 1902 by José Ferreras Pagán does not list a sugar hacienda in the Patillas area named Merle, San Isidro or San Isidoro or owned by any person with last name Merle or Amadeo.  However, it states that Central Columbia in Maunabo processed sugarcane from several small growers including one Dr. Amadeo.   The only reference to a Hacienda Merle found is in Gloria Tapia Rios book La Central Lafayette: Riqueza, Desarrollo y Politicaen el Sureste de Puerto Rico on page 191 which states that after the pass of Hurricane San Ciriaco:

"...In view of the need to process their sugarcane so as not to lose the harvest, many growers signed contracts to process their sugarcane at Central Columbia.  Ingenio Quebrada Palma of Naguabo stopped grinding in 1899; and the Carolina of the Sucn. José Ortiz, and the Hacienda Marle (sic) of Dr. [Antonio] Amadeo, among so many others, began processing their sugarcane at Columbia". 

Adjacent to the ruins photographed below are the remains of a mansion that belonged to Bernardo Merle, built in 1906 per a tile plaque on one of its walls and identified as Hacienda San Isidro per the name at the bottom of staircase.  Details of its interior can be seen in the YouTube video below and on this webpage.  Based on the bathroom and kitchen fixtures and the interior decor in the linked website, it is evident the mansion was remodeled in recent years but is now again abandoned.

Ebay has or had for sale a handwritten letter signed by B. Merle dated in 1915 acknowledging payment in full of the proceeds of the sale of twelve oxen.  The business name on the letterhead is Hacienda San Isidoro, adding some confusion as to the real name of the hacienda even though on the YouTube Video linked it can be clearly seen it was Hacienda San Isidro.  

It is therefore reasonable to believe that Bernardo Merle acquired Hacienda San Isidro and its land from Dr. Amadeo sometime before his 1904 and built this mansion in 1906 where he lived until his death in 1918