Ryan Kilian exchanged texts with his girlfriend, Jena Christiansen, Monday afternoon, when the messages suddenly stopped.

He soon learned why: Jena and her mother, Karen, who were driving, were on their way home. when an 800-pound rock fell from a truck passing them in an opposite direction on a Rosemount highway. Both were declared dead on the scene. The truck was not found.

On Wednesday night, the police located the driver of a house in Inver Grove Heights. Joseph Paul Czeck, 33, of Hastings, was charged on Thursday with a criminal manslaughter for driving a vehicle in a grossly careless manner and a charge manager. criminal operation causing serious bodily injury for leaving an accident site after a collision. He was detained in Dakota County Jail.

"It's just sad for the family," said Rosemount Police Chief Mitchell Scott. "It's something that could have been avoided."

A representative of the Christiansen family said that they were not ready to talk. But in a series of posts Thursday, Kilian said that he was heartbroken.

"How is it / Jena Christiansen, you are my world / Awaken me from this nightmare," he wrote on Facebook on Wednesday. that the two women were "loving people" and that Karen Christiansen was kind and hospitable to him. Jena was eccentric and sarcastic, he says, often making him laugh so much that he was crying.

Jena, 32, lived in Superior, Wisconsin, and worked as a restaurant manager at Red Lobster. Karen, 67, has retired from her position as Training Representative at Dakota County Technical College in Rosemount.

Kilian said that he and Jena were moving to the Twin Cities, where she had just started the red lobster in Bloomington. "All his employees liked him," said Kilian

. At CCMAT, Karen had helped students seeking vocational training and businesses who wanted their employees to learn new skills. "She was a very sweet person and a hard worker," said Marlo Teal, a colleague and friend, in a message. "She was so patient with the students and helped a lot of people."

Teal added that she was close to her family, including Jena: "There was a lot of love."

On Monday, Karen Christiansen had gone to lunch with friends. Jena picked her up after work. Karen seated in the driver's seat and both headed for the family residence at Shoreview

Police said they were questioning witnesses and were finalizing the investigation after the arrest of Czeck

"We think he knew"

Scott says that Czeck refused to make a statement when he was arrested, only saying that he wanted a lawyer.

Scott said that it was not clear whether Czeck was aware that the rock had come out of the truck or the accident. But the police chief said that he had his suspicions.

"We think he knew but … we do not know what he thought."

Czeck has six minor driving offenses on his 2003 record, including speeding and not wearing a seatbelt. He seems to own a landscape business, Scott said, and the truck he was driving sported a logo that said "Czeck Services."

Scott said that the accident was rare, but that it's not unusual for people to secure their charges. He recalled a man who died on Interstate 494 several years ago after a tire broke through his windshield.

Scott estimated that the rock that caused the accident is about 3 feet by 3 feet and weighs about 800 pounds. A video of himself with Jena on Facebook Wednesday, written above: "I miss her."

He said that she was a free spirit and did not care what others thought. "She just wanted to be happy," he says.

As for Czeck, Kilian says, he should no longer be able to drive, let alone carry things. "I want him to be punished," said Kilian. "He ruined the lives of so many people."