A news conference will be held at 5 p.m. to announce charges and provide additional details.
Six members of the Martinez family were found dead in their Gage Park home in the 5700-block of South California Avenue around 1:30 p.m. on Feb. 4 after a relative called police and asked for a well-being check.
PHOTOS: 6 family members murdered in Gage Park home
The victims were identified as Noe Martinez Sr., 62; his wife, Rosaura Martinez, 58; their children Noe Martinez Jr., 38, and Maria Herminia Martinez, 32; as well as their grandchildren Leonardo Cruz, 13, and Alexis Cruz, 10, according to the Cook County Medical Examiner's Office. Their deaths were ruled homicides.
Autopsies found that five of the six victims were beaten and stabbed. Maria Martinez was the only victim who was shot.
Only one member of the family, sibling Victoria Martinez, survived.