Kasandra Perkins,22 and Jovan Belcher,25 were arguing over Kasandra arriving home past midnight, before he shot her to death and then committed suicide in front of his coaches, according to the Kansas City Star.

A friend of Perkins told the newspaper that their argument started about 1 am Saturday when Perkins arrived at the couple's home from a Trey Songz concert and after having drinks with friends.

The Kansas City Chiefs' linebacker, reportedly "was mad" that she'd stayed out so late, according to the friend.

Belcher shot and killed Perkins around 8 am Saturday at their home in Kansas City as his mother who was visting from New York, watched. 

Then Belcher drove to the Kansas City Chiefs' practice facility and committed suicide in front of the Chiefs' head coach and General Manager.

The couple had a three-month-old daughter called Zoey who is in care of her paternal grandmother..

Police is investigating the murder-suicide and the official motive of the killings remains unclear. However, a male source linked to Belcher says that the NFL player and Perkins had a long term conflict and that the tragic incident was the result of his severe drinking, head concussions and prescription drugs.

The friend said that Perkins and Belcher argued on a regular basis and as a result of their conflicts, Perkins and their 3-month-old daughter moved out.

Recently Belcher convinced her and she moved back with him with their daugther, according to a series of emails sent to Deadspin.

The source, which allegedly was a person close to Belcher, also said that Belcher drank "a lot" on a daily basis, took narcotics for pain, had head concussions and was suffering from short term memory loss.

"If you review the footage of the Cincinnati game he took a few hits to the head directly [...] he was dazed and was suffering from short term memory loss," the source told Deadspin in an email. 

Perkins' friends who spoke to the Kansas City Star, said she was loving and a very good person.

"She was a very good person; she was fun to be around and very loving," her friend Brianne York, 21 told the paper. "I don't know why he'd want to hurt her like that."