SAN ANTONIO - A San Antonio man was arrested Thursday on suspicion of possessing child pornography, according to police.
Police began investigating the allegations against Matthew Allen Cyr, 38, in May, according to his arrest affidavit.
Cyr's former common-law wife called police to report him after she discovered Cyr had a sexual relationship with the woman's 16-year-old relative.
The woman told police she had previously suspected Cyr was having a relationship with the teen but knew for sure after discovering what was on his phone.
The teen's younger brother accessed Cyr's phone in April while Cyr was asleep on the couch, according to his arrest affidavit.
The brother found explicit photos of the siblings on the phone, including Instagram messages they exchanged.
Cyr allegedly asked the woman not to call police after he admitted to having "done things" with the 16-year-old girl, according to the affidavit.
Cyr's bail was set at $50,000, jail records show.
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