In the days before the toddler died after suffering a severe bacterial infection, Cottrell Short and his younger sister slept in portable cribs in the basement of a duplex packed with 17 people living amid garbage, rotting food and dead animals.

An autopsy recently revealed the boy suffered from sepsis, in which the bloodstream is overwhelmed by bacteria, and had an elevated level of sedative medication in his system. The report also detailed a long list of injuries to Cottrell, including a fresh skull fracture, several deep bruises, foot injuries, a broken arm, a broken leg and an "extremely serious burn" on his right hand.

A month before Cottrell died in February, a doctor's examination showed the toddler in good health and no apparent injuries, said police. The baby's mother, Shacara Foster, 27, was charged in March with neglect of a child for her treatment of him. Last week, the Hennepin County medical examiner ruled Cottrell's death a homicide.

Although no one has been arrested in connection with the homicide, Foster remains in jail without bail because the neglect charge violated her probation on a previous robbery conviction. Her next court hearing is May 9.

Police have been called to the duplex at 3730 Hillview Lane in St. Bonifacius 35 times since 2008. The parents of Foster's boyfriend have rented the duplex since 2009. The most recent calls ranged from disorderly conduct to medical calls and 911 hang-ups, said police.

Authorities are being tight-lipped about the homicide investigation because of its sensitive nature, said Minnetrista Police Chief Paul Falls. He described it as a complex case involving a number of people and wouldn't say if new charges were imminent.

Last week, Hennepin County Sheriff Rich Stanek said "this little boy died a horrible, horrible death." Legal proceedings have begun against Foster concerning her parental rights over her daughter, who was examined and found not to have any signs of physical abuse, said the complaint alleging neglect by Foster.

Cottrell, who would have been 2 this summer, stopped breathing and was rushed from the duplex Feb. 10 to a nearby hospital, where he died the next day. Foster was arrested last month and charged with felony child neglect.

In addition to Cottrell, Foster and her infant daughter, the duplex also was home to Foster's 20-year-old boyfriend, and his 11 siblings, mother and stepfather, according to investigators. Foster and her boyfriend had been dating since the summer of 2011. He wasn't Cottrell's biological father, said the complaint.

The boyfriend slept in a room in the basement where Cottrell and Foster's daughter used portable cribs that each had "heavy blankets and other bedding in them inappropriate" for babies, according to the criminal complaint.

The boyfriend told police that he had smoked marijuana the night before Cottrell died and called Foster home because Cottrell had a fever of 102.6 degrees. Foster, who had been in St. Paul, returned after several calls from her boyfriend to find Cottrell not breathing. Two people who know Foster told police she had a history of leaving her children with "just anyone" to get away from them, the complaint said. Foster told police that her boyfriend and his siblings saw the boyfriend's 3-year-old brother push Cottrell down a flight of stairs the day before Cottrell died.

The duplex is in foreclosure. Kim Hatz, who has lived on the block for 25 years, said she had no inkling about conditions inside the duplex. The children played frequently in the park next door to their home, she said, and would come across the street to ask her husband to fill up their bicycle tires.

"The kids that would come up to our house were very nice, very polite," she said. "It's just so sad this happened."

The duplex is large, she said, and in the 1980s was a group home. The portion rented by the family has seven bedrooms, she said, and the smaller portion was rented to a single woman.

Another neighbor said he hopes the city will now buy the property, tear down the building and make the land part of the adjacent park.

Tim Hicks, who has lived on the street since 2001, said a steady stream of people have rented the duplex, and that few of them stayed for more than a few months. The current family had been there a bit longer, he said, and the kids never caused trouble while playing outdoors.  "What I saw of them seemed fine," he said, "but I guess behind closed doors, you never know."

Staff writer Paul Walsh contributed to this report. • 612-673-4465 • 612-673-7388