The bloodied bodies of a husband and wife were found on the floor of their home in San Jose, California, next to a message reading, "Sorry, my first kill was clumsy," according to local media reports.
Golam Rabbi, 59, and his wife Shamima Rabbi, 57, were found by a neighbour on Monday. Both were shot at least once, police said.
Authorities have interviewed the couple���s 17-year-old son and are now trying to locate their eldest son for questioning.
"At this time he is not considered a suspect but may have information regarding this incident," San Jose Police spokesman Albert Morales said in a statement.
The creepy message was found by friends of Mr and Mrs Rabbi, who entered the home in search of the couple after they had been missing for several days.
They reported the note was scrawled on the floor with a pen.
Police have not confirmed the existence of the message, but do believe the person behind the killings was known to the family.
The Rabbi family had lived in America for 30 years after moving from Bangladesh and were active members of the Evergreen Islamic Centre (EIC) in San Jose.
Other members described the couple as “polite, gentle and kind”.
"For them to have met this violent end is just beyond comprehension for me,” one friend told New York Daily News.
Police said they were working hard to bring the case to a close.
"Our homicide investigators are working diligently to try and conduct a thorough and complete investigation, so that we may bring closure to this horrible crime and provide answers," Morales said.
On Wednesday, the EIC posted on their Facebook page that the couple's bodies could not be released by the coroner until their eldest son had been located.
"According to the laws of California, the bodies of Mithu (Shamima) and Golam Rabbi can only be released by the coroner's office to their adult son, Haseeb. Haseeb is currently missing. The younger son is a juvenile and therefore cannot sign the papers to receive the bodies," the post read.
"Per the law, this situation will remain in effect until May 4th after which if the elder son is still not available then the coroner's office will release the bodies to the siblings of Mithu and Golam Rabbi."
The EIC will start planning burial once the bodies have been released.
Police continue to search for the couple's son.
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News break – April 27