Wiese said he could not confirm the relationship between Tysen and the girl, but media reports say she was his girlfriend.
The case bears some similarities to the plot of William Shakespeare's classic play Romeo and Juliet.
"The impact that it had on the boy - there's a logical connection," Wiese told the Washington Post. "He did this within hours of the conversation happening via text."
The girl, whose name was not released, has been charged with malicious use of telecommunication service, punishable by up to six months in juvenile detention; and using a computer to commit a crime, which carries up to a year in punishment. Both are misdemeanor charges.
The incident happened on March 14.
Nothing seemed amiss when he came home from school earlier that day, said the boy's mother, Katrina Goss, of Marquette, Michigan. He seemed happy and was proud that he had gone to his tutoring session without being reminded, Goss told the Washington Post. She baked him some treats as a reward. After dinner, Tysen went up to his room.
Shortly after 10pm, Goss went to each of her three sons' rooms to tuck them in. Tysen's door was locked, but she was able to open it with her key. At first, she thought her middle son was hiding or playing a trick because he wasn't in his bed.
"I went in, and I thought he was being silly," Goss told the Post. "I ended up finding him in the closet . ... I tried to hurry up and lift him up. I was screaming. I told my oldest son to call 911. My littlest one was bawling."
Goss said the paramedics were able to revive Tysen. The boy was hospitalised for three weeks before he died last Wednesday at a Detroit-area hospital.
Goss said her son often used Snapchat. The night he died, she said he was texting and talking on Snapchat with the 13-year-old girl, who was using someone else's account when she told Tysen that his girlfriend had died. No one warned her son that it was all a prank, Goss said.
"She used her friend's account to make it even more proof that she'd died," Goss said. "He was so innocent, so kindhearted and so naive that he completely believed her and he took his own life."
Wiese, the prosecutor, said there was some reference to Snapchat in the text exchange, but it's unclear what was said on the social media app because investigators have been unable to obtain those messages.
In an interview with the Associated Press, Goss described her son's death as the result of "a twisted, sick joke" delivered in the form of cyberbullying on social media.
She said she wants to raise awareness about how social media platforms influence children's actions.
"I want him to basically be the face of the cause. It's a serious issue that I feel is completely skirted," Goss said. "The way that children are using social media currently in this day and age is just terrible."
Goss said her son and the girl were attending the same school. Although the prank happened outside of school, she said officials have failed to do enough to protect her son.
The Post was unable to reach the girl or her family, and it was not immediately clear if she has a lawyer.
Marquette Area Public Schools Superintendent William Saunders said school officials agree with Goss' statements about the dangers of social media, but their knowledge of the incident is limited because it happened outside of school.
In 2011, Michigan Governor Rick Snyder, signed a bill requiring schools to have anti-bullying policies in place. The bill, called "Matt's Safe School Law," was named after a 14-year-old who killed himself in 2002 after he was assaulted at school.
About 1 in 5 students during the 2012-13 school year reported being bullied either through insults, rumors or physical harm, according to a 2015 report by the US Department of Education. Cyberbullying was less frequent and affected about 1 in 14 students.
According to a 2016 study by the American Academy of Pediatrics, the number of suicides among adolescents have increased dramatically in recent decades. The study found that being a victim of bullying has a "clear relationship"with committing or thinking of committing suicide.
Furthermore, the study also found that excessive Internet use was "strongly associated with higher levels of depression"and thoughts or attempts to commit suicide.
Goss said her son, an athlete who played hockey, travel soccer and golf, did not have any underlying issues that would've hinted that he'd hurt himself.
"He was perfectly happy and fine. There was no additional sadness that was occurring. He had tons of friends," she said. "Anybody who knows him knows he's a shining star."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• Samaritans 0800 726 666
• If it is an emergency and you feel like you or someone else is at risk, call 111.
