UPDATED 04/12/11 7:54 a.m.

CHICAGO (CBS) – The Chicago Police Department is investigating the mysterious death of an officer, whose visitation was held Monday night.

Kevin Robinson, 42, reportedly got sick at work, after accidently inhaling some kind of cleaning solution that had been sprayed on March 7. After spending weeks in the hospital, Robinson died last week on April 4. 

But Robinson’s friends and family still really don’t know why or how he died, CBS 2’s Mai Martinez reports.

Robinson, nicknamed “Kevo,” was known for what his friends and family called his “Kool-Aid smile.”  

“The smile that he had on his face every day showed nothing but joy,” Robinson’s friend and work partner Curtis Smith said.

Smith says Robinson’s smile lifted everyone’s spirits, even on the tough streets of Chicago.  

“He cared about the work that we did out there — you know, trying to get the bad guys,” Smith said.

LISTEN: Newsradio 780’s Bernie Tafoya reports

Robinson, a tactical officer and 15-year-veteran of the department, died last Monday after spending weeks in the hospital following an incident at work at the 22nd District in Morgan Park.

According to a police blog, Robinson reportedly inhaled some kind of cleaning substance after a maintenance man sprayed a chemical solution. Smith was with him, but couldn’t talk about what happened because of an ongoing investigation. Smith no other officers got sick that day from the cleaning solution.  

Smith says he visited Robinson every day at the hospital and was there the day he passed.  

“I recall telling him that I loved him, and that’s not something male partners tell each other,” Smith said.

Now, Smith says, all he wants to know is why. 

“I’m looking forward to something coming out, letting us know a definitive reason for what happened, why my partner lost his life,” he said.

Robinson is survived by many family members, including his two teen-aged children. His friends and family will likely not have answers about his death anytime soon. The medical examiner’s office says it could be six to eight weeks before the can determine Robinson’s cause of death.  

His funeral is scheduled for 11 a.m. Tuesday at Third Baptist Church of Chicago on West 95th Street.