When he died 7 Mar 1961 he was 64 years old and was born in Toledo. Surviving him was his mother, Alvina Gross, Toledo and brother Henry in Monroe, MI. Knowing that he had a brother Henry, pins it down that "Lena" is Alvina in the 1900 Toledo census.
Alvina GROSS survivied Walter by almost 6 months; she died 2 Sep 1961 at age 87. I doubt that Alvina's obit would be helpful unless she had a surviving brother. But that's not a certainty either if Alvina was married before she married Walter's father.
Before you spend 20 bucks for each cert, I'll check for a death record, ca 1899, on my next trip to the library.