(CNN) -- The death certificate for Boston bombings suspect Tamerlan Tsarnaev, who died April 19 after a shootout with police, says he died of "gunshot wounds of torso and extremities" and "blunt trauma to head and torso," according to the owner of the funeral parlor that currently holds Tsarnaev's body.
Peter Stefan, owner of Graham Putnam & Mahoney Funeral Parlors in Worcester, Massachusetts, read the death certificate to CNN over the phone Friday evening. He said it has yet to be filed with the city of Boston.
There is no gravesite chosen yet for the 26-year-old Tsarnaev, Stefan said. He said that if he can't find a cemetery plot, he plans to ask the government to find a grave.
"Everyone deserves to be buried," Stefan said.
Tsarnaev's uncle, Ruslan Tsarni, claimed his nephew's body, according to family spokeswoman Heda Saratova. The family plans an independent autopsy before burying the body somewhere in Massachusetts, she said.
Stefan acknowledged plans for a second autopsy.
Authorities say Tsarnaev and his younger brother, Dzhokhar, carried out the April 15 bombings at the Boston Marathon. The attacks killed three people and wounded more than 260 others.
The brothers later killed a Massachusetts Institute of Technology police officer, authorities say.
Dzhokhar Tsarnaev, 19, is being held at a federal Bureau of Prisons medical facility in Devens, Massachusetts, charged with using a weapon of mass destruction, a charge that carries the death penalty.
He is being treated for gunshot wounds to the head, neck, legs and hands that he received in the April 19 shootout with police that led to his brother's death. Tamerlan Tsarnaev was shot in the gunbattle, and Dzhokhar apparently ran over his brother as he tried to flee in a car, authorities have said.
It is not known whether the "blunt trauma" listed on Tamerlan Tsarnaev's death certificate relates to injuries from the car.
As part of their continuing investigation, investigators have found explosives residue in the apartment that the elder Tsarnaev shared with his wife and young daughter, a source briefed on the investigation said Friday.
The residue turned up in at least three places at the apartment in Cambridge, Massachusetts, the source said: the kitchen table, the kitchen sink and the bathtub.
U.S. law enforcement officials briefed on the progress of the investigation have provided CNN with other critical details:
-- Dzhokhar Tsarnaev told investigators that he and his brother built the devices in Tamerlan's home;
-- He said the brothers originally planned a suicide attack on the city's massive Independence Day celebration, which draws about 500,000 people and is televised nationally on CBS;
-- Dzhokhar Tsarnaev told investigators that the brothers chose to target the Boston Marathon only a day or two before the event. They changed their plans because their bombs were ready sooner than they expected.
The officials spoke on background because they were not authorized to speak with the media.
Katherine Russell, Tsarnaev's widow, has remained largely out of view since her husband's death, staying inside her parents' Rhode Island home.
Her attorney, Amato DeLuca, says the 24-year-old knew nothing about plans to bomb the race, and reports of her husband's involvement came as an "absolute shock" to Russell and her family.
Three of Dzhokhar Tsarnaev's friends have been charged in connection with the case.
Azamat Tazhayakov and Dias Kadyrbayev were charged Wednesday with conspiring to discard potentially incriminating items from Dzhokhar Tsarnaev's dorm room. Robel Phillipos was charged with making false statements to investigators.
The FBI is examining Dzhokhar Tsarnaev's laptop, two federal law enforcement officials told CNN.
Authorities have said they believe the brothers acted alone but are investigating whether they could have learned from or been aided by terror groups, including groups overseas.
CNN's Dave Alsup, Susan Candiotti, Carol Cratty, Marina Carver and Deborah Feyerick contributed to this report.